90pts求调

#include<iostream>
using namespace std;
int a,b,c,d,s,e;
bool x = false,y = false;
int main() {
    cin >> a >> b >> c >> d;
    for(int i = 1;i <= a;i++){
        s = (i - 1) * c;e = i * c;        
        if(s >= b && (s - b) % d == 0) x = true;
        if(e >= b && (e - b) % d == 0) y = true;
        if(!x && !y){
            cout << "Yes" << endl;
            return 0;
        }
    }
    cout << "No" << endl;
}