#include<stdio.h>

int main(){
    int n,m,p,q,now;
    
    scanf("%d %d %d %d", &n, &m, &p, &q);
    
    now = 1;
    while(n>0){
        now++;
        if(now%12-p < 0){
            n -= m;
        }
        else if(p+q-1-now%12>=0){
            n -= 2*m;
        }
        else{
            n -= m;
        }
    }
    
    printf("%d",now-1);
    return 0;
}