// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include "bits/stdc++.h"
using namespace std;
using ll = long long int;
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

int main()
{
    ios::sync_with_stdio(false); cin.tie(0);

    int w, z; cin >> w >> z;
    long double b; cin >> b;
    long double ans = (w + z) * (1 + b);
    long long fin = ans + 0.1;
    cout << fin << '\n';
}