MOD = 10**9 + 7
def nCr(n, r, MOD):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])
            result %= MOD

    return result
n, a, b = map(int,input().split())
ans = pow(2,n,MOD)-1-nCr(n,a,MOD)-nCr(n,b,MOD)
while ans < 0:
    ans += MOD
print(ans) MOD = 10**9 + 7 MOD 10**9 + 7 10**9 10 9 7 def nCr(n, r, MOD):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])
            result %= MOD

    return result nCr if n - r < r: r = n - r
     n - r < r n - r n r r if r == 0: return 1
     r == 0 r 0 if r == 1: return n

     r == 1 r 1 n - r + k + 1 for k in range(r) for k in range(r) k range(r) range r for k in range(r) n - r + k + 1 n - r + k n - r n r k 1 numerator = [n - r + k + 1 for k in range(r)] numerator [n - r + k + 1 for k in range(r)] k + 1 for k in range(r) for k in range(r) k range(r) range r for k in range(r) k + 1 k 1 denominator = [k + 1 for k in range(r)] denominator [k + 1 for k in range(r)] for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

     p range(2,r+1) range 2 r+1 r 1 pivot = denominator[p - 1] pivot denominator[p - 1] denominator p - 1 p 1 if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

     pivot > 1 pivot 1 offset = (n - r) % p offset (n - r) % p n - r n r p for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

     k range(p-1,r,p) range p-1 p 1 r p numerator[k - offset] /= pivot numerator[k - offset] numerator k - offset k offset pivot denominator[k] /= pivot denominator[k] denominator k pivot result = 1 result 1 for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])
            result %= MOD

     k range(r) range r if numerator[k] > 1:
            result *= int(numerator[k])
            result %= MOD

     numerator[k] > 1 numerator[k] numerator k 1 result *= int(numerator[k]) result int(numerator[k]) int numerator[k] numerator k result %= MOD result MOD return result result n n r r MOD MOD n, a, b = map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split a b ans = pow(2,n,MOD)-1-nCr(n,a,MOD)-nCr(n,b,MOD) ans pow(2,n,MOD)-1-nCr(n,a,MOD)-nCr(n,b,MOD) pow(2,n,MOD)-1-nCr(n,a,MOD) pow(2,n,MOD)-1 pow(2,n,MOD) pow 2 n MOD 1 nCr(n,a,MOD) nCr n a MOD nCr(n,b,MOD) nCr n b MOD while ans < 0:
    ans += MOD ans < 0 ans 0 ans += MOD ans MOD print(ans) print ans ans = pow(2,n,MOD)-1-nCr(n,a,MOD)-nCr(n,b,MOD) pow(2,n,MOD)-1-nCr(n,a,MOD)-nCr(n,b,MOD) ans MOD = 10**9 + 7 10**9 + 7 MOD b = map(int,input().split()) map(int,input().split()) b ans += MOD MOD ans a, b = map(int,input().split()) map(int,input().split()) a n, a, b = map(int,input().split()) map(int,input().split()) n def nCr(n, r, MOD):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])
            result %= MOD

    return result def nCr(n, r, MOD):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])
            result %= MOD

    return result nCr
MOD = 10**9 + 7
def nCr(n, r, MOD):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])
            result %= MOD

    return result
n, a, b = map(int,input().split())
ans = pow(2,n,MOD)-1-nCr(n,a,MOD)-nCr(n,b,MOD)
while ans < 0:
    ans += MOD
print(ans)
