#include "bits/stdc++.h"
using namespace std;
#define ll long long int
#define rep(i,n) for( int i = 0; i < n; i++ )
#define rrep(i,n) for( int i = n; i >= 0; i-- )
#define REP(i,s,t) for( int i = s; i <= t; i++ )
#define RREP(i,s,t) for( int i = s; i >= t; i-- )
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define INF 2000000000
#define mod 1000000007
#define INF2 1000000000000000000


int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
	int A[3];
	rep(i, 3) cin >> A[i];
	sort(A, A + 3);
	rep(i, 1000) {
		int tmp = (A[2] - A[0]) / 6;
		A[0] += tmp;
		A[2] -= tmp * 2;
		sort(A, A + 3);
		//cout << A[0] << " " << A[1] << " " << A[2] << endl;
	}
	while (A[2] - A[0] >= 3) {
		A[2] -= 2;
		A[0] += 1;
		sort(A, A + 3);
	}
	cout << A[0] << endl;

    return 0;
}