#include<bits/stdc++.h> 
using namespace std;
int x,y,z,i;
int main()
     cin>>x>>y>>z;
     i=z+x+y;
     
     printf(%b%.1f,i,i/3);
}
/**************************************************************
	Problem: 1602
	User: chenyichuen
	Language: C++
	Result: Compile Error
****************************************************************/