90pts求调

#include <iostream>
using namespace std;
bool f[305];
int n,y,s,t;
int main()
{
    cin >> n >> y >> s >> t;
    for(int i = y;i<n*s;i++)
    {
        if((i-y)%t==0)f[i]=1;
    }
    bool flag = 0;
    for(int i = 0;i<=n;i+=s)
    {
        if(!f[i]&&!f[i+s])flag=1;
    }
    if(flag)cout << "Yes";
    else cout <<"No";
    return 0;
}