/* -*- coding: utf-8 -*-
 *
 * 740.cc:  No.740 幻の木 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int n, m, p, q;
  scanf("%d%d%d%d",&n, &m, &p, &q);
  p--;
  int m2 = m * 2;
  int y = (12 + q) * m;
  int a = n / y, b = n % y;

  int c = a * 12;
  if (b <= p * m) c += (b + m - 1) / m;
  else if (b <= p * m + q * m2) c += p + (b - p * m + m2 - 1) / m2;
  else c += p + q + (b - p * m - q * m2 + m - 1) / m;

  printf("%d\n", c);
  return 0;
}