#include <iostream>

short ObtainMultiplicativeInverse(int a, int b, int s0 = 1, int s1 = 0)
{
    return b==0? s0: ObtainMultiplicativeInverse(b, a%b, s1, s0 - s1*(a/b));
}

int main(int argc, char* argv[])
{
    std::cout << ObtainMultiplicativeInverse(42, 2017) << std::endl;
    return 0;
}