#include<bits/stdc++.h>
using namespace std;
using ll=long long;
using pii=pair<int,int>;

#define all(a) a.begin(),a.end()
#define pb push_back
#define sz(a) ((int)a.size())

signed main(){
    ios_base::sync_with_stdio(0),cin.tie(0);
    int a,b; double c; cin >> a >> b >> c;
    a/=10,b/=10;
    int x=c*10+0.5;
    cout << (a+b)*(10+x) << "\n";
}