#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> Pll;
typedef pair<ld, ld> Pdd;
template<typename T>
using MaxHeap = priority_queue<T>;
template<typename T>
using MinHeap = priority_queue<T, vector<T>, greater<T>>;
#define REP(i, n) for(int i = 0; i < n; i++)
#define REPR(i, n) for(int i = n; i >= 0; i--)
#define FOR(i, m, n) for(int i = m; i < n; i++)
#define FORR(i, m, n) for(int i = m; i >= n; i--)
#define INF (ll)1e17
#define ALL(v) v.begin(), v.end()
#define SZ(x) ((ll)(x).size())
#define bit(n) (1LL<<(n))
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define cauto const auto&
#define cdebug if (debug_mode) cerr
#define dump(x) if (debug_mode) cerr << #x << " = " << (x) << "\t";
#define SP << " " <<
#define TB << "\t" <<

#ifdef _LOCAL
    bool debug_mode = true;
#else
    bool debug_mode = false;
#endif

int main()
{

    ll W, Z, A;
    double B;
    cin >> W >> Z >> B;

    A = B * 10;

    cout << (W + Z) / 10 * (A+10) << endl;

    return 0;
}