Fastpow-mod

long long fast_pow(int a,int n)
{
    long long result = 1;
    long long power = n;
    long long value = a;
    while(power>0)
    {
        if(power&1)
            {result = result*value;
            result = result%1000000007;}
        value = value*value;
        value = value%1000000007;
        //power /= 2;
        power >>= 1;
    }
    return result;
}