#include <bits/stdc++.h>


using namespace std;


#define ar array
#define ll long long
#define For(i,k,n) for(int i=k;i<n;i++)
#define Forll(i,k,n) for(long long int i=k;i<n;i++)
#define Forull(i,k,n) for(long long int i=k;i<n;i++)



const ll MOD = 1e9 + 7;
const ll INF = 1e9;

void solve(){
   int a,b,c;
   cin>>a>>b>>c;

   if(a*a+b*b<c*c)
   cout<<"Yes"<<"\n";
   else
   cout<<"No"<<"\n";

   

   








   
   

   
   





   









    

    









    

       

   

   




   




   







    

    
    


    


	

   
    

    

   

    










    


    }






    
    
    

    






int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

     ll int tc=1;
    //cin >> tc;
    for (ll int t = 1; t <= tc; t++) {
        //cout << "Case #" << t  << ": ";
        solve();
        
    }
}


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


int main(){
    int v,t,s,d,p;
    cin>>v>>t>>s>>d;
    
    if (t*v<=d &&  d<=s*v)
    {
        cout<<"No";
    }
    else
    {
        cout<<"Yes";
    }
    
    
    
    

  return 0;
}