#include<bits/stdc++.h>
#include<cstring>
#include<queue>
#include<set>
#include<stack>
#include<vector>
#include<map>
#define ll long long
using namespace std;
const int N=1e5+10;
const int M=2023;
const int inf=0x3f3f3f3f;
ll a,b,c;
int main()
{
	cin>>a>>b>>c;
	cout<<a*c+b*c;
		return 0;
}