ReachingPoints.cpp

#include <bits/stdc++.h>
using namespace std;

bool reachingPoints(int sx, int sy, int tx, int ty) {
    while (true) {
        if (sx == tx && sy == ty) {
            return true;
        }
        if (sx > tx || sy > ty) {
            return false;
        }
        if (tx > ty) {
            tx -= (tx / ty) * ty;
        } else {
            ty -= (ty / tx) * tx;
        }
    }
}

bool reachingPointsOpt(int sx, int sy, int tx, int ty) {
    while (sx < tx && sy < ty) {
        if (tx > ty) {
            tx %= ty;
        } else {
            ty %= tx;
        }
    }
    return (sx == tx && sy <= ty && (ty - sy) % sx == 0) || (sy == ty && sx <= tx && (tx - sx) % sy == 0);
}

int main() {
    int a, b, c, d;
    cin >> a >> b >> c >> d;
    cout << reachingPoints(a, b, c, d);
}