n,a,b=map(int,input().split())
mod=10**9+7

#modあり
def pow_speed(x,n):
    res = 1
    while n > 0:
        if n & 1 == 1:
            res *= x
        x *= x
        x%=mod
        n >>= 1
    return res

#nCx(mod)
def comb_speed(n,x):
    rec=1
    for i in range(n-x+1,n+1):
        rec=rec*i%mod
    rec2=1
    for i in range(1,x+1):
        rec2=rec2*i%mod
    rec2=pow_speed(rec2,mod-2)
    return (rec*rec2)%mod

print((pow_speed(2,n)-comb_speed(n,a)-comb_speed(n,b)-1)%mod) n,a,b=map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split a b mod=10**9+7 mod 10**9+7 10**9 10 9 7 def pow_speed(x,n):
    res = 1
    while n > 0:
        if n & 1 == 1:
            res *= x
        x *= x
        x%=mod
        n >>= 1
    return res

#nCx(mod) pow_speed res = 1 res 1 while n > 0:
        if n & 1 == 1:
            res *= x
        x *= x
        x%=mod
        n >>= 1
     n > 0 n 0 if n & 1 == 1:
            res *= x
         n & 1 == 1 n & 1 n 1 1 res *= x res x x *= x x x x%=mod x mod n >>= 1 n 1 return res res x x n n def comb_speed(n,x):
    rec=1
    for i in range(n-x+1,n+1):
        rec=rec*i%mod
    rec2=1
    for i in range(1,x+1):
        rec2=rec2*i%mod
    rec2=pow_speed(rec2,mod-2)
    return (rec*rec2)%mod comb_speed rec=1 rec 1 for i in range(n-x+1,n+1):
        rec=rec*i%mod
     i range(n-x+1,n+1) range n-x+1 n-x n x 1 n+1 n 1 rec=rec*i%mod rec rec*i%mod rec*i rec i mod rec2=1 rec2 1 for i in range(1,x+1):
        rec2=rec2*i%mod
     i range(1,x+1) range 1 x+1 x 1 rec2=rec2*i%mod rec2 rec2*i%mod rec2*i rec2 i mod rec2=pow_speed(rec2,mod-2) rec2 pow_speed(rec2,mod-2) pow_speed rec2 mod-2 mod 2 return (rec*rec2)%mod (rec*rec2)%mod rec*rec2 rec rec2 mod n n x x print((pow_speed(2,n)-comb_speed(n,a)-comb_speed(n,b)-1)%mod) print (pow_speed(2,n)-comb_speed(n,a)-comb_speed(n,b)-1)%mod pow_speed(2,n)-comb_speed(n,a)-comb_speed(n,b)-1 pow_speed(2,n)-comb_speed(n,a)-comb_speed(n,b) pow_speed(2,n)-comb_speed(n,a) pow_speed(2,n) pow_speed 2 n comb_speed(n,a) comb_speed n a comb_speed(n,b) comb_speed n b 1 mod a,b=map(int,input().split()) map(int,input().split()) a def pow_speed(x,n):
    res = 1
    while n > 0:
        if n & 1 == 1:
            res *= x
        x *= x
        x%=mod
        n >>= 1
    return res

#nCx(mod) def pow_speed(x,n):
    res = 1
    while n > 0:
        if n & 1 == 1:
            res *= x
        x *= x
        x%=mod
        n >>= 1
    return res

#nCx(mod) pow_speed n,a,b=map(int,input().split()) map(int,input().split()) n b=map(int,input().split()) map(int,input().split()) b def comb_speed(n,x):
    rec=1
    for i in range(n-x+1,n+1):
        rec=rec*i%mod
    rec2=1
    for i in range(1,x+1):
        rec2=rec2*i%mod
    rec2=pow_speed(rec2,mod-2)
    return (rec*rec2)%mod def comb_speed(n,x):
    rec=1
    for i in range(n-x+1,n+1):
        rec=rec*i%mod
    rec2=1
    for i in range(1,x+1):
        rec2=rec2*i%mod
    rec2=pow_speed(rec2,mod-2)
    return (rec*rec2)%mod comb_speed mod=10**9+7 10**9+7 mod
n,a,b=map(int,input().split())
mod=10**9+7

#modあり
def pow_speed(x,n):
    res = 1
    while n > 0:
        if n & 1 == 1:
            res *= x
        x *= x
        x%=mod
        n >>= 1
    return res

#nCx(mod)
def comb_speed(n,x):
    rec=1
    for i in range(n-x+1,n+1):
        rec=rec*i%mod
    rec2=1
    for i in range(1,x+1):
        rec2=rec2*i%mod
    rec2=pow_speed(rec2,mod-2)
    return (rec*rec2)%mod

print((pow_speed(2,n)-comb_speed(n,a)-comb_speed(n,b)-1)%mod)