#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template<class T>
using V = std::vector<T>;
#define REP(i, n) for (ll i = (ll)0; i < (ll)(n); i++)
#define REPS(i, s, n) for (ll i = (ll)(s); i < (ll)(n); i++)
#define RREP(i, n) for (ll i = (ll)(n); i > (ll)0; i--)
#define RREPS(i, s, n) for (ll i = (ll)(n); i > (ll)(s); i--)
#define ALL(c) std::begin((c)), std::end((c))
struct io {
    io() { cin.tie(0)->sync_with_stdio(0); }
} caller;

int main() {
    int w, z;
    double b;
    cin >> w >> z >> b;

    cout << (w + z) * (b + 1) << endl;

    return 0;
}