#include <iostream>
using namespace std;

int main(){
    int p, d, m, s, count = 0;
    cin>>p>>d>>m>>s;
    while(s>0){
        s-=p;
        if(s>=0) count++;
        if(p-d>m) p-=d;
        else p = m;
    }
    cout<<count;
    return 0;
}