#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
int main() {
  int n,m,p,q,ans=0,M=1;
  cin >> n >> m >> p >> q;
  while(n>0) {
      if(M>=p&&M<=p+q-1) {
          n-=m*2;
      }
      else {
          n-=m;
      }
      M++,ans++;
      if(M>=13) {
          M=1;
      }
  }
  cout << ans << endl;
}