#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int howManyGames(int p, int d, int m, int s) {

    int games = 0;
    
    while((s-p) >= 0)
    {
        s = s - p;
        games++;
        
        if((p - d) >= m)
            p = p - d;
        else
           p = m; 
    }
    
    return games;
}

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;
}