#include<bits/stdc++.h>
#include<random>
using namespace std;
using ll=long long;
using ld=long double;
using P=pair<ll,ll>;
#define MOD 1000000007LL
#define INF 1000000000LL
#define EPS 1e-10
#define FOR(i,n,m) for(ll i=n;i<(ll)m;i++)
#define REP(i,n) FOR(i,0,n)
#define DUMP(a) REP(d,a.size()){cout<<a[d];if(d!=a.size()-1)cout<<" ";else cout<<endl;}
#define ALL(v) v.begin(),v.end()
#define UNIQUE(v) sort(ALL(v));v.erase(unique(ALL(v)),v.end());
#define pb push_back

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int n,m,p,q;
	cin>>n>>m>>p>>q;
	ll ans=1,mnt=1;
	while(1) {
		if(mnt>=p&&mnt<p+q) n-=2*m;
		else n-=m;
		if(n>0) ans++;
		else break;
		mnt+=1;
		if(mnt==13) mnt=1;
	}
	cout<<ans<<endl;
	return 0;
}