#include <bits/stdc++.h>

#define int long long

using namespace std;
#define rep(i,s,n) for(int i = s;i<n;i++)
#define repe(i,s,n) for(int i = s;i<=n;i++)
#define rrep(i,s,n) for(int i = (n)-1;i>=(s);i--)
#define all(v) (v).begin(),(v).end()
#define pb push_back
#define fi first
#define se second
typedef long long ll;
typedef pair<int,int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
typedef pair<pint,int> P1;
typedef pair<int,pint> P2;
static const ll maxLL = (ll)1 << 62;
const ll MOD=1000000007,INF=1e18;
int dy[]={-1,0,1,0};
int dx[]={0,1,0,-1};

int n,m,p,q;
 
signed main(){
	cin>>n>>m>>p>>q;
	int cnt=0;
	int sum=0;
	rep(i,1,12+1){
	    if(p<=i&&i<=p+q-1)sum+=m*2;
	    else sum+=m;
	    
	}
	cnt=n/sum;
	n%=sum;
	rep(i,1,12+1){
	    if(p<=i&&i<=p+q-1)n-=m*2;
	    else n-=m;
	    if(n<=0){
	        cout<<i+cnt*12<<endl;
	        return 0;
	    }
	}
	
	
	
	return 0;
}