#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

typedef long long i64;

const int N = 110;

int n, m, k;
int s[N][N];

int main() {
    scanf("%d%d%d", &n, &m, &k);

    for (int i = 1; i <= n; i ++ ) 
        for (int j = 1; j <= m; j ++ ) {
            scanf("%d", &s[i][j]);
            s[i][j] += s[i - 1][j];
        }

    int res = 1e9;
    for (int x = 1; x <= n; x ++ ) 
        for (int y = x; y <= n; y ++ ) 
            for (int i = 1, j = 1, v = 0; i <= m; i ++ ) {
                v += s[y][i] - s[x - 1][i];
                while (j < i && v - (s[y][j] - s[x - 1][j]) >= k) v -= (s[y][j] - s[x - 1][j]), j ++ ;
                if (v >= k) res = min(res, (y - x + 1) * (i - j + 1));
            }

    if (res == 1e9) res = -1;
    printf("%d\n", res);

    return 0;
}