include <bits/stdc++.h>

using namespace std;

int main() {
int a1,a2,a3,a4,a5;
float ave;
cin>>a1>>a2>>a3>>a4>>a5;
ave=(a1+a2+a3+a4+a5)/5.0;//注意这个5.0，是转化成浮点数的关键
printf("%.1f",ave);
return 0;
}