#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main(){
	int w,z;
	double b;
	cin>>w>>z>>b;
	w/=10;
	z/=10;
	b*=10;
	int bb=b+10;
	cout<<(w+z)*bb<<endl;
}