#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

int main() {
  int N, M, P, Q;
  scanf("%d %d %d %d", &N, &M, &P, &Q);

  int ans = 0;
  int end = P + Q - 1;
  while (N > 0) {
    int month = ans % 12 + 1;
    if (month >= P && month <= end) {
      N -= 2 * M;
    } else {
      N -= M;
    }
    ans++;    
  }
  printf("%d\n", ans);
  return 0;
}