#include <cmath>
#include <cstdlib>
#include <iostream>
using namespace std;
int main(){
int h1,h2,h3,h4,n,l,k;
cin>>h1>>h2>>h3>>h4;
n=abs(h1-h2);
l=abs(h1-h3);
k=abs(h1-h4);
if(n<l&&n<k){
cout<<h2;
}else if(l<n&&l<k){
cout<<h3;
}else if(k<n&&k<l){
cout<<h4;
}
if(nl){
if(h2<h3){
cout<<h2;
}else if(h3<h2){
cout<<h3;
}
}else if(nk){
if(h2<h4){
cout<<h2;
}else if(h4<h2){
cout<<h4;
}
}else if(l==k){
if(h3<h4){
cout<<h3;
}else if(h4<h3){
cout<<h4;
}
}
return 0;
}
