#include <iostream>
using namespace std;

int main(){
    int r, g, b; cin >> r >> g >> b;
    auto f = [&](int x){
        int plus = 0, minus = 0;
        if(r > x) plus += (r-x)/2;
        else minus += x-r;
        if(g > x) plus += (g-x)/2;
        else minus += x-g;
        if(b > x) plus += (b-x)/2;
        else minus += x-b;
        return plus >= minus;
    };
    int ac = -1, wa = 1 << 30;
    while(wa-ac > 1){
        int wj = (wa+ac)/2;
        if(f(wj)) ac = wj;
        else wa = wj;
    }
    cout << ac << endl;
    return 0;
}