#include <bits/stdc++.h>

using namespace std;

#define REP(i, n) for(int i = 0; i < n; i++)
#define VSORT(v) sort(v.begin(), v.end())

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    vector<int> stone(3);
    REP(i, 3) cin >> stone[i];
    VSORT(stone);
    while (stone[2] >= stone[0] + 2) {
        stone[2] -= 2;
        stone[0]++;
        VSORT(stone);
    }

    cout << stone[0] << endl;
    return 0;
}