#include<bits/stdc++.h>
using namespace std;
int main()
{
    int t,i,j,k,l,m,n,p,d,s;
    scanf("%d%d%d%d",&p,&d,&m,&s);
    int c=0;
    int bg=p;
    int cur=0;
    int pass=0;
    int nc;
    while(1)
    {

        if(bg<=m)
        {
            pass=1;
            bg=m;

        }
        if(cur+bg<=s)
        {
            cur+=bg;
            c++;
        }
        else
            break;
        if(pass==0)
            bg-=d;


    }
    printf("%d\n",c);
}