#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <math.h>
int main(void)
{
    int leaf,lost,wind,swind,monthcnt=0;
    scanf("%d %d %d %d",&leaf,&lost,&swind,&wind);
    while(1)
    {
        for(int i=1;i<=12;i++)
        {
            monthcnt++;
            if(swind<=i&&i<swind+wind)
            {
                leaf-=lost*2;
            }
            else
            {
                leaf-=lost;
            }
            if(leaf<=0)
            {
                goto escape;
            }
        }
    }
    escape:
    printf("%d",monthcnt);
}