#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) {
    // Return the number of games you can buy
    if(s < m)
        return 0;
    int ctr =0;
    int s1 = s;
    if(s>=p){
    s = s-p;
    ctr++;}
    else
        return 0;
    int c = p-d;
    while(c > m && s>= c){
        s = s-c;
        c = c-d;
        ctr++;
    }
    while(s >= m && c <= m){
        s = s-m;
        ctr++;
            
    }
    return ctr;
}

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;
}