#include <iostream>
using namespace std;
int main()
{
	int a,b,c,t,s;
	cin>>a>>b>>c;
	if(a < b)
	{
		t = a;
		a = b;
		b = t;
	}
	if(a < c)
	{
		t = a;
		a = c;
		c = t;
	}
	if(b < c)
	{
		t = b;
		b = c;
		c = t;
	}
	s = a * b + b * c * 2 + a * c * 2;
	cout<<s;
	return 0;
}
/**************************************************************
	Problem: 1340
	User: admin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/