#include <bits/stdc++.h> 
using namespace std;
using ll =long long;
#define all(v) v.begin(),v.end()
 #define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)

ll INF=2e18;


int main() {
    ios::sync_with_stdio(false);
  cin.tie(0);
ll W,Z;cin>>W>>Z;
double B;cin>>B;

ll ans=B*(W+Z);
ans+=W+Z;
cout<<ans<<endl;
}