#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<ll(n);i++)
#define REP(i,k,n) for(ll i=k;i<ll(n);i++)
#define all(a) a.begin(),a.end()
#define eb emplace_back
#define lb(v,k) (lower_bound(all(v),k)-v.begin())
#define ub(v,k) (upper_bound(all(v),k)-v.begin())
#define fi first
#define se second
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define UNIQUE(a) sort(all(a));a.erase(unique(all(a)),a.end())
#define decimal cout<<fixed<<setprecision(10)
#define summon_tourist cin.tie(0);ios::sync_with_stdio(false)
using ll=long long;
using P=pair<ll,ll>;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
constexpr ll inf=1001001001001001;
constexpr int INF=1001001001;
constexpr int mod=1000000007;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
void YesNo(bool b){if(b)out("Yes");else out("No");}
void yesno(bool b){if(b)out("yes");else out("no");}
void YESNO(bool b){if(b)out("YES");else out("NO");}
ll modpow(ll a,ll b){ll c=1;while(b>0){if(b&1){c=a*c%mod;}a=a*a%mod;b>>=1;}return c;}
vi calc(ll x){vi v;while(x>0){v.eb(x%10);x/=10;}reverse(all(v));return v;}

int main(){
    ll a,b,n,m;
    cin>>a>>b>>n>>m;
    if(a==b) out(a);
    else if(a>b){
        ll p=(a-b)/(n+1);
        out(b+p);
    }
    else{
        ll p=(b-1)/(m+1);
        out(a+p);
    }
}