#include <bits/stdc++.h>

using namespace std;
typedef long long LL;

// P1082 [NOIP2012 提高组] 同余方程

//扩展欧几里得
LL exgcd(LL a, LL b, LL &x, LL &y) {
    if (!b) {
        x = 1, y = 0;
        return a;
    }
    LL d = exgcd(b, a % b, y, x);
    y -= a / b * x;
    return d;
}

int main() {
    LL a, b;
    scanf("%lld %lld", &a, &b);
    LL x, y;
    exgcd(a, b, x, y);
    printf("%d\n", (x % b + b) % b);
    return 0;
}