#include <iostream>
#include <fstream>

using namespace std;

typedef long long ll;

ifstream in("inversmodular.in");
ofstream out("inversmodular.out");

ll a, b, d, yy, xx;

ll gcd(ll a, ll b, ll &x, ll &y)
{
    if(!b)
    {
        x=1, y=0;
        return a;
    }
    ll rez, y1, x1;
    rez=gcd(b, a%b, x1, y1);
    x=y1;
    y=x1-(a/b)*y1;
    return rez;
}

int main()
{
    in>>a>>b;
    d=gcd(a, b, xx, yy);
    if(xx<=0) xx=b+a%b;
    out<<xx;
    return 0;
}