#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

int howManyGames(int p, int d, int m, int s) {
    int count=0;
   while(s>0){
       if(p>m){
           count++;
           s-=p;
           p-=d;
       }
       else if(p<=m){
           count++;
           s -= m;
           p=m;
       }
   }
    if(s<0)
        return count-1;
    else
        return count;
}

int main() {
    int p; 
    int d; 
    int m; 
    int s; 
    scanf("%i %i %i %i", &p, &d, &m, &s);
    int answer = howManyGames(p, d, m, s);
    printf("%d\n", answer);
    return 0;
}