#include<iostream>

#include<cstring>

#include<cstdlib>

#include<cstdio>

#include<algorithm>

#define ll long long

using namespace std;

const int maxn=;

int n,m,k;

ll f[maxn][maxn][][][][];

void read(int &k)

{

    int f=;k=;char c=getchar();

    while(c<''||c>'')c=='-'&&(f=-),c=getchar();

    while(c<=''&&c>='')k=k*+c-'',c=getchar();

    k*=f;

}

ll dfs(int x,int y,int l,int r,int u,int d)

{

    if(x<y)swap(x,y),swap(l,d),swap(u,r);

    if(u<d)swap(u,d);if(l<r)swap(l,r);

    if(f[x][y][l][r][u][d]!=-)return f[x][y][l][r][u][d];

    ll ans=1ll*(x*y-k)*(x*y-k);

    if(l||r||(u&&d))for(int i=;i<x;i++)ans=min(ans,dfs(i,y,l,r,u,)+dfs(x-i,y,l,r,,d));

    if(u||d||(l&&r))for(int i=;i<y;i++)ans=min(ans,dfs(x,i,l,,u,d)+dfs(x,y-i,,r,u,d));

//    printf("%d %d %d %d %d %d %d\n",x,y,l,r,u,d,ans);

    return f[x][y][l][r][u][d]=ans;

}

int main()

{

    read(n);read(m);read(k);

    memset(f,-,sizeof(f));

    printf("%lld\n",dfs(n,m,,,,));

    return ;

}