#include <bits/stdc++.h>
using namespace std;int main(){
int al,h2,h3,h4;
cin >> al >> h2 >> h3 >> h4;
int cnt = h2;
int mi = abs(al-h2);
int d3 = abs(al-h3);
if(d3 < mi || (d3 == mi && h3 < cnt)){
cnt = h3;
mi = d3;
}
int d4 = abs(al-h4);
if(d4 < mi || (d4 == mi && h4 < cnt)){
cnt = h4;
mi = d4;
}
cout << cnt;
return 0;
}
