MOD = pow(10, 9)+7

def combi(n, k, MOD):
    numer = 1
    for i in range(n, n-k, -1):
        numer *= i
        numer %= MOD
    denom = 1
    for j in range(k, 0, -1):
        denom *= j
        denom %= MOD
    return (numer*(pow(denom, MOD-2, MOD)))%MOD

def main():
    n, a, b = map(int, input().split())
    allsum = pow(2, n, MOD)
    s1 = combi(n, a, MOD)
    s2 = combi(n, b, MOD)
    ans = (allsum - s1 - s2 - 1)%MOD
    print(ans)

if __name__ == "__main__":
    main() MOD = pow(10, 9)+7 MOD pow(10, 9)+7 pow(10, 9) pow 10 9 7 def combi(n, k, MOD):
    numer = 1
    for i in range(n, n-k, -1):
        numer *= i
        numer %= MOD
    denom = 1
    for j in range(k, 0, -1):
        denom *= j
        denom %= MOD
    return (numer*(pow(denom, MOD-2, MOD)))%MOD combi numer = 1 numer 1 for i in range(n, n-k, -1):
        numer *= i
        numer %= MOD
     i range(n, n-k, -1) range n n-k n k -1 numer *= i numer i numer %= MOD numer MOD denom = 1 denom 1 for j in range(k, 0, -1):
        denom *= j
        denom %= MOD
     j range(k, 0, -1) range k 0 -1 denom *= j denom j denom %= MOD denom MOD return (numer*(pow(denom, MOD-2, MOD)))%MOD (numer*(pow(denom, MOD-2, MOD)))%MOD numer*(pow(denom, MOD-2, MOD)) numer pow(denom, MOD-2, MOD) pow denom MOD-2 MOD 2 MOD MOD n n k k MOD MOD def main():
    n, a, b = map(int, input().split())
    allsum = pow(2, n, MOD)
    s1 = combi(n, a, MOD)
    s2 = combi(n, b, MOD)
    ans = (allsum - s1 - s2 - 1)%MOD
    print(ans) main n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b allsum = pow(2, n, MOD) allsum pow(2, n, MOD) pow 2 n MOD s1 = combi(n, a, MOD) s1 combi(n, a, MOD) combi n a MOD s2 = combi(n, b, MOD) s2 combi(n, b, MOD) combi n b MOD ans = (allsum - s1 - s2 - 1)%MOD ans (allsum - s1 - s2 - 1)%MOD allsum - s1 - s2 - 1 allsum - s1 - s2 allsum - s1 allsum s1 s2 1 MOD print(ans) print ans if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main MOD = pow(10, 9)+7 pow(10, 9)+7 MOD def combi(n, k, MOD):
    numer = 1
    for i in range(n, n-k, -1):
        numer *= i
        numer %= MOD
    denom = 1
    for j in range(k, 0, -1):
        denom *= j
        denom %= MOD
    return (numer*(pow(denom, MOD-2, MOD)))%MOD def combi(n, k, MOD):
    numer = 1
    for i in range(n, n-k, -1):
        numer *= i
        numer %= MOD
    denom = 1
    for j in range(k, 0, -1):
        denom *= j
        denom %= MOD
    return (numer*(pow(denom, MOD-2, MOD)))%MOD combi def main():
    n, a, b = map(int, input().split())
    allsum = pow(2, n, MOD)
    s1 = combi(n, a, MOD)
    s2 = combi(n, b, MOD)
    ans = (allsum - s1 - s2 - 1)%MOD
    print(ans) def main():
    n, a, b = map(int, input().split())
    allsum = pow(2, n, MOD)
    s1 = combi(n, a, MOD)
    s2 = combi(n, b, MOD)
    ans = (allsum - s1 - s2 - 1)%MOD
    print(ans) main
MOD = pow(10, 9)+7

def combi(n, k, MOD):
    numer = 1
    for i in range(n, n-k, -1):
        numer *= i
        numer %= MOD
    denom = 1
    for j in range(k, 0, -1):
        denom *= j
        denom %= MOD
    return (numer*(pow(denom, MOD-2, MOD)))%MOD

def main():
    n, a, b = map(int, input().split())
    allsum = pow(2, n, MOD)
    s1 = combi(n, a, MOD)
    s2 = combi(n, b, MOD)
    ans = (allsum - s1 - s2 - 1)%MOD
    print(ans)

if __name__ == "__main__":
    main()
