#include <bits/stdc++.h>
using namespace std;
int tmp,tong;
int main(){
for (int i = 0; i < 3; i++){
cin >> tmp;
if (tmp % 2 == 0){
tong += tmp / 2;
}
else {
tong += (tmp / 2) + 1;
}
}
cout << tong;
}
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