formula1_eu

#include <bits/stdc++.h>

using namespace std;
ifstream fin("formula1.in");
ofstream fout("formula1.out");
int C, N, K;
long long sol, suma;
int main()
{
    fin>>C>>K>>N;
    if(C==1)
    {
        sol=1LL*(2*K-1)*(2*K-1);
        fout<<sol;
        return 0;
    }
    for(int i=1; i<=N; i++)
    {
        sol=1LL*2*i*i-2*i;
        suma+=sol;
    }
    sol=(long long)sqrtl(1LL*2*suma+1);
    if(sol%2==0)
        sol--;
    fout<<sol*sol;
    return 0;
}