#include<sstream>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())
#define indexOf(v,x) (find(all(v),x)-v.begin())




int main(){
	int x,y,x2,y2;
	cin>>x>>y>>x2>>y2;
	int ans=max(x,y);
	if(x==y&&x2<x&&y2<y&&(long long)x*y2==(long long)x2*y)ans++;
	cout<<ans<<endl;
	return 0;
}