#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(p > s) {
                return 0;
        }
        int cnt = 1, xx = p;
        s -= p;
        while(s > 0) {
                if(p - d >= m)
                        p -= d;
                else
                        p = m;
                s -= p;
                if(s >= 0)
                        cnt++;
        }
        return cnt;
}

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;
}