#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) {
    int g=0,tmp;
  while(p>m)
  {
  p=p-d;
   tmp=tmp+p;
     if(tmp>s)
     {
       g=g-1;
     }
  }
  if(p<m)
  {
    do{
      tmp=tmp+m;
      g=g+1;
    }while(tmp<=s);
  }
   return g+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;
}