#include<bits/stdc++.h>
using namespace std;
long long ans,a,b,c;
int main(){
    cin >> a >> b >> c;
    if(a < b){
        if(c - b <= 0){
            a += c;
            c = 0;
        }
        else{
            c -= b-a;
            a = b;
        }
    }
    else{
        if(c - a <= 0){
            b += c;
            c = 0;
        }
        else{
            c -= a-b;
            b = a;
        }
    }
    a += c / 2;
    b += c / 2;
    for(int i = 1;;i++){
        if(a-i < 0||b-i < 0)
            break;
        a -= i;
        b -= i;
        ans = i;

    }
   cout << ans;
    return 0;
}