#include<bits/stdc++.h>
using namespace std;
int main()
{
	int a,b,c;
	cin>>a>>b>>c;
	if(a<b) swap(a,b);
	if(a<c) swap(a,c);
	if(b<c) swap(b,c);
	cout<<(a*b*1)+(a*c*2)+(b*c*2);    
	return 0;
}

/**************************************************************
	Problem: 1340
	User: ccf
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/