import math
from math import gcd,pi,sqrt
INF = float("inf")
MOD = 10**9 + 7

import sys
sys.setrecursionlimit(10**6)
import itertools
from collections import Counter,deque
def i_input(): return int(input())
def i_map(): return map(int, input().split())
def i_list(): return list(i_map())
def i_row(N): return [i_input() for _ in range(N)]
def i_row_list(N): return [i_list() for _ in range(N)]
def s_input(): return input()
def s_map(): return input().split()
def s_list(): return list(s_map())
def s_row(N): return [s_input for _ in range(N)]
def s_row_str(N): return [s_list() for _ in range(N)]
def s_row_list(N): return [list(s_input()) for _ in range(N)]

def main():
    n,a,b = i_map()
    s = pow(2,n,MOD) - 1

    def fur(n,r):
        p,q = 1, 1
        for i in range(r):
            p = p*(n-i)%MOD
            q = q*(i+1)%MOD
        return (p * pow(q,MOD-2,MOD)) % MOD

    print((s - fur(n,a) - fur(n,b)) % MOD)



if __name__=="__main__":
    main() import math math from math import gcd,pi,sqrt INF = float("inf") INF float("inf") float "inf" MOD = 10**9 + 7 MOD 10**9 + 7 10**9 10 9 7 import sys sys sys.setrecursionlimit(10**6) sys.setrecursionlimit sys setrecursionlimit 10**6 10 6 import itertools itertools from collections import Counter,deque def i_input(): return int(input()) i_input def i_map(): return map(int, input().split()) i_map def i_list(): return list(i_map()) i_list i_input() for _ in range(N) for _ in range(N) _ range(N) range N for _ in range(N) i_input() i_input def i_row(N): return [i_input() for _ in range(N)] i_row N N i_list() for _ in range(N) for _ in range(N) _ range(N) range N for _ in range(N) i_list() i_list def i_row_list(N): return [i_list() for _ in range(N)] i_row_list N N def s_input(): return input() s_input def s_map(): return input().split() s_map def s_list(): return list(s_map()) s_list s_input for _ in range(N) for _ in range(N) _ range(N) range N for _ in range(N) s_input def s_row(N): return [s_input for _ in range(N)] s_row N N s_list() for _ in range(N) for _ in range(N) _ range(N) range N for _ in range(N) s_list() s_list def s_row_str(N): return [s_list() for _ in range(N)] s_row_str N N list(s_input()) for _ in range(N) for _ in range(N) _ range(N) range N for _ in range(N) list(s_input()) list s_input() s_input def s_row_list(N): return [list(s_input()) for _ in range(N)] s_row_list N N def main():
    n,a,b = i_map()
    s = pow(2,n,MOD) - 1

    def fur(n,r):
        p,q = 1, 1
        for i in range(r):
            p = p*(n-i)%MOD
            q = q*(i+1)%MOD
        return (p * pow(q,MOD-2,MOD)) % MOD

    print((s - fur(n,a) - fur(n,b)) % MOD) main n,a,b = i_map() n i_map() i_map a b s = pow(2,n,MOD) - 1 s pow(2,n,MOD) - 1 pow(2,n,MOD) pow 2 n MOD 1 def fur(n,r):
        p,q = 1, 1
        for i in range(r):
            p = p*(n-i)%MOD
            q = q*(i+1)%MOD
        return (p * pow(q,MOD-2,MOD)) % MOD

     fur p,q = 1, 1 p 1 q 1 for i in range(r):
            p = p*(n-i)%MOD
            q = q*(i+1)%MOD
         i range(r) range r p = p*(n-i)%MOD p p*(n-i)%MOD p*(n-i) p n-i n i MOD q = q*(i+1)%MOD q q*(i+1)%MOD q*(i+1) q i+1 i 1 MOD return (p * pow(q,MOD-2,MOD)) % MOD (p * pow(q,MOD-2,MOD)) % MOD p * pow(q,MOD-2,MOD) p pow(q,MOD-2,MOD) pow q MOD-2 MOD 2 MOD MOD n n r r print((s - fur(n,a) - fur(n,b)) % MOD) print (s - fur(n,a) - fur(n,b)) % MOD s - fur(n,a) - fur(n,b) s - fur(n,a) s fur(n,a) fur n a fur(n,b) fur n b MOD if __name__=="__main__":
    main() __name__=="__main__" __name__ "__main__" main() main def s_row_str(N): return [s_list() for _ in range(N)] def s_row_str(N): return [s_list() for _ in range(N)] s_row_str def s_row(N): return [s_input for _ in range(N)] def s_row(N): return [s_input for _ in range(N)] s_row def s_map(): return input().split() def s_map(): return input().split() s_map def i_list(): return list(i_map()) def i_list(): return list(i_map()) i_list def i_row(N): return [i_input() for _ in range(N)] def i_row(N): return [i_input() for _ in range(N)] i_row INF = float("inf") float("inf") INF def s_input(): return input() def s_input(): return input() s_input def i_row_list(N): return [i_list() for _ in range(N)] def i_row_list(N): return [i_list() for _ in range(N)] i_row_list def i_input(): return int(input()) def i_input(): return int(input()) i_input def s_row_list(N): return [list(s_input()) for _ in range(N)] def s_row_list(N): return [list(s_input()) for _ in range(N)] s_row_list def i_map(): return map(int, input().split()) def i_map(): return map(int, input().split()) i_map def s_list(): return list(s_map()) def s_list(): return list(s_map()) s_list def main():
    n,a,b = i_map()
    s = pow(2,n,MOD) - 1

    def fur(n,r):
        p,q = 1, 1
        for i in range(r):
            p = p*(n-i)%MOD
            q = q*(i+1)%MOD
        return (p * pow(q,MOD-2,MOD)) % MOD

    print((s - fur(n,a) - fur(n,b)) % MOD) def main():
    n,a,b = i_map()
    s = pow(2,n,MOD) - 1

    def fur(n,r):
        p,q = 1, 1
        for i in range(r):
            p = p*(n-i)%MOD
            q = q*(i+1)%MOD
        return (p * pow(q,MOD-2,MOD)) % MOD

    print((s - fur(n,a) - fur(n,b)) % MOD) main MOD = 10**9 + 7 10**9 + 7 MOD
import math
from math import gcd,pi,sqrt
INF = float("inf")
MOD = 10**9 + 7

import sys
sys.setrecursionlimit(10**6)
import itertools
from collections import Counter,deque
def i_input(): return int(input())
def i_map(): return map(int, input().split())
def i_list(): return list(i_map())
def i_row(N): return [i_input() for _ in range(N)]
def i_row_list(N): return [i_list() for _ in range(N)]
def s_input(): return input()
def s_map(): return input().split()
def s_list(): return list(s_map())
def s_row(N): return [s_input for _ in range(N)]
def s_row_str(N): return [s_list() for _ in range(N)]
def s_row_list(N): return [list(s_input()) for _ in range(N)]

def main():
    n,a,b = i_map()
    s = pow(2,n,MOD) - 1

    def fur(n,r):
        p,q = 1, 1
        for i in range(r):
            p = p*(n-i)%MOD
            q = q*(i+1)%MOD
        return (p * pow(q,MOD-2,MOD)) % MOD

    print((s - fur(n,a) - fur(n,b)) % MOD)



if __name__=="__main__":
    main()
