快速幂模板

long long  qpow(long long  n,long long  k,long long m)
{
    long long  ans = 1;
    long lon g nn = n % m;
    while(k>0)
    {
        if(k&1)
            ans =ans * nn % m;
        nn = nn * nn % m;
        k>>=1;
    }
    return ans;
}