#include <iostream>


int main()
{
    int a,b,n;
    scanf("%d %d %d",&a,&b,&n);
    if (a+b == n){
        printf("%d\n",n);
        if (n/2){
            printf("%s","chetnoe");
        }
    }else {
        printf("%d",a+b);

    }
    return 0;
}