#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
const int N = 1e3 + 5;

int arr[N][N];
int maxn[N][N], minn[N][N];

void solve(){
    int a, b, n;
    cin >> a >> b >> n;
    for(int i = 1; i <= a; i++){
        for(int j = 1; j <= b; j++){
            cin >> arr[i][j];
            maxn[i][j] = minn[i][j] = arr[i][j];
        }
    }
    int ans = 0x3f3f3f3f;
    for(int k = 2; k <= n; k++){
        for(int i = 1; i + k <= a + 1; i++){
            for(int j = 1; j + k <= b + 1; j++){
                maxn[i][j] = max(max(maxn[i][j], maxn[i + 1][j + 1]), max(maxn[i][j + 1], maxn[i + 1][j]));
                minn[i][j] = min(min(minn[i][j], minn[i + 1][j + 1]), min(minn[i][j + 1], minn[i + 1][j]));
                ans = k == n ? min(ans, maxn[i][j] - minn[i][j]) : 0x3f3f3f3f;
                //cout << ans << ' ';
            }
        }
    }
    cout << ans << '\n';
}

int main(){
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
    return 0;
}