#include<bits/stdc++.h>
using namespace std;
int main(){
    int a,b,c,s;
    cin>>a>>b>>c;
    if(a<b) swap(a,b);
    if(a<c) swap(a,c);
    if(b<c) swap(b,c);
    s=a*b+a*c*2+b*c*2;
    cout<<s<<endl;
    return 0;
}
/**************************************************************
	Problem: 1340
	User: HUANGYIBO
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/