#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
#define REP(i,n) for(int i=0; i<int(n); i++)
#define FOR(i,m,n) for(int i=int(m); i<int(n); i++)
#define ALL(obj) (obj).begin(),(obj).end()
#define VI vector<int>
#define VLL vector<long long>
#define VVI vector<vector<int>>
#define VVLL vector<vector<long long>>
#define VC vector<char>
#define VS vector<string>
#define VVC vector<vector<char>>
#define fore(i,a) for(auto &i:a)

typedef pair <int, int> P;
template<class T> bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; }
const int  INF = 2147483647;
const ll INFL = 9223372036854775807;
const ll mod = 1000000007;



int main() {
	
	int n, m, p, q;
	cin >> n >> m >> p >> q;
	int ans = 0;
	int month = 1;
	int k = n / (m*(12 + q));
	ans += 12 * k;
	n -= m * (12 + q)*k;
	while (n>0) {
		n -= m;
		ans++;
		if (p <= month && month < p + q) {
			n -= m;
		}
		month++;
		if (month == 13)month = 1;
	}


	cout << ans << endl;


}