#include<iostream>
#include<algorithm>
using namespace std;
#define REP(i,n) for(int i=0;i<n;i++)

int main() {
	int stone[3], ans = 0, x;
	REP(i,3)
		cin >> stone[i];
	sort(stone, stone + 3);
	while (stone[0]>=0) {
		x = stone[0];
		ans += x;
		REP(i,3)
			stone[i] -= x;
		stone[2] -= 2;
		stone[0]++;
		sort(stone, stone + 3);
	}
	cout << ans << endl;
}