#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(p>=m && (s-p)>=0)
    {
        count++;
        s=s-p;      
        if((p-d)>=m)
        p=p-d;
        else
            p=m;
       //printf("p=%d d=%d m=%d s=%d count=%d\n",p,d,m,s,count ); 
    }
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;
}