#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) {
   // printf("%d",s);
    int count=0;
    while(s>=0){
       // printf("%d",s);
        if(count==0&&s>=p)
        {
          //  printf("%d",s);
            count++;
          //  printf("dd");
            s=s-p;
            if(p-d>=m)
                p=p-d;
            else p=m;
        }
        else if(count>0&&s>=p){
     count++;
            s=s-p;
            
            if(p-d>=m)
                p=p-d;
            else p=m;
        }
        else return count;
            
        
    }
    return count;
    // Return the number of games you can buy
}

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;
}