#include <iostream>
#include<algorithm>
using namespace std;
int main() {
	int a[3];
	cin>>a[0]>>a[1]>>a[2];
	while(1)
	{
		sort(a,a+3);
		if(a[2]-a[0]<3)break;
		a[0]++;
		a[2]-=2;
	}
	cout<<a[0]<<endl;
	return 0;
}