package com.codegym.task.task04.task0424;
/*
Three numbers
*/
import java.io.*;
import java.util.Scanner;
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int a = Integer.parseInt(reader.readLine());
int b = Integer.parseInt(reader.readLine());
int c = Integer.parseInt(reader.readLine());
if(a == b && a != c){
System.out.println(c);
}else if(a != b && a == c){
System.out.println(b);
}else if(b == a && b != c){
System.out.println(c);
}else if(b == c && b != a){
System.out.println(a);
}else if(c == a && c != b){
System.out.println(b);
}else if(c == b && c != a){
System.out.println(a);
}
}
}