#include <iostream>

using namespace std;

long long f(long long A, long long B) {
    long long r = A % B;

    while(r) {
        A = B;
        B = r;
        r = A % B;
    }

    return B;
}

int main() {
    long long A, B;

    cin >> A >> B;

    long long N = 1;
    long long cmmdc = (A + 1) * (B + 1) / f(A + 1, B + 1);

    for(long long i = 2;; ++i) {
        long long x = 1LL * (A + i) * (B + i) / f(A + i, B + i);
        if(x < cmmdc) {
            cmmdc = x;
            N = i;
        }

        if(cmmdc < min(A + i, B + i)) {
            break;
        }
    }

    cout << N << '\n';

    return 0;
}