#include <bits/stdc++.h>
using namespace std;
int main()
{
float a,b,c,tbc;
cout<<"a="; cin>>a;
cout<<"b="; cin>>b;
cout<<"c="; cin>>c;
tbc=(a+b+c)/3;
cout<<fixed<setprecision(1)<<tbc;
return 0;
}
uses crt;
var a,b,c:longint;
begin
clrscr;
write('a=');readln(a);
write('b=');readln(b);
write('c=');readln(c);
write((a+b+c)div 3);
readln;
end.