#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 = 0;
    int count = 0;
    int temp;
    
    for(int i = 0; i < m; i++) {
        if( i == 0 && sum <= s){
            sum += p;
            count++;
        }
        if(i < m && temp != m && sum <= s){
            sum = sum + p - d;
            temp = temp - d ;
            count++;
        }
        if (temp == m && sum <= s){
            sum = sum + m;
            count++;
        }
    }
    return (count+1);
}

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;
}