#include<stdio.h>
#include<assert.h>
int howManyGames(int p,int d,int m,int s);
int howManyGames(int p,int d,int m,int s)
{
    int i,sum=0,count=-1;
    while(sum<=s)
    {
        if(p<m)
        {
            sum=sum+m;
            count++;
        }
        else if(p>=m)
        {
            sum=sum+p;
            p=p-d;
            count++;
        }
    }
    return(count);
}
int main()
{
    int m,p,d,s,answer;
    printf("enter p,d,m,s: ");
    scanf("%d%d%d%d",&p,&d,&m,&s);
    assert(p>=1&&p<=100);
    assert(m>=1&&m<=p);
    assert(d>=1&&d<=100);
    assert(s>=1&&s<=10000);
     answer=howManyGames(p,d,m,s);
    printf("%d",answer);
    return 0;
}