#include<bits/stdc++.h> 
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;
}
	 

/**************************************************************
	Problem: 1340
	User: yangjunwen
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/