#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
    int sum = p;
    int c = 1; //already bought first item
    int k = 1;
    while(sum <= s && (p-(k*d)) >= m)
    {
        //c = c + 1;
        sum = sum + (p-(k*d));
        k = k+1;
        c = c+1;
    }
    while(sum <= s)
    {
        c = c + 1;
        sum = sum + m;
    }
    if(sum > s)
        return c-1;
    else
        return c;
}

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;
}