//Normal

#define _GLIBCXX_DEBUG
#define ll long long
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

void print(auto a){
  cout << a;
}

void prints(auto a){
  cout << a << " ";
}

void prints(){
  cout << " ";
}

void printl(auto a){
  cout << a << endl;
}

void printl(){
  cout << endl;
}

void fix(int n){
  cout << fixed << setprecision(n);
}

int siz(string s){
  return (int)s.size();
}

int main(){
  int N, M, P, Q; cin >> N >> M >> P >> Q;

  int lest = N;
  for(int i = 1; i <= N; i++){
    int j = i%12;

    if(j == 0) j = 12;

    P <= j and j < P+Q ? lest -= M*2 : lest -= M;

    if(lest <= 0){
      printl(i);

      return 0;
    }
  }
}