[NHSPC 2019] D. 獵人與斯芬克斯

// #pragma GCC target("avx2")
#pragma GCC optimize("O3", "unroll-loops")

// #include <bits/extc++.h>
// using namespace __gnu_pbds;

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define double long double
// template <typename T>
// using pbds_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
using pii = pair<int, int>;
template<typename T>
using prior = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using Prior = priority_queue<T>;

#define X first
#define Y second
#define ALL(x) (x).begin(), (x).end()
#define eb emplace_back
#define pb push_back

#define fastIO() ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
#define RANDOM() random_device __rd; \
                 mt19937 __gen = mt19937(__rd()); \
                 uniform_int_distribution<int> __dis(0, 1); \
                 auto rnd = bind(__dis, __gen);

const int INF = 1E18;
const int mod = 1E9 + 7;

int32_t main() {
    fastIO();

    int k, n, m;
    cin >> k >> n >> m;

    vector<vector<int>> vec(n+1, vector<int>(m+1, 0));
    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= m; ++j) cin >> vec[i][j];
    }

    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= m; ++j) {
            vec[i][j] += vec[i-1][j] + vec[i][j-1] - vec[i-1][j-1];
        }
    }

    int ans = 0;
    for (int i = 0; i <= n; ++i) {
        for (int j = i+1; j <= n; ++j) {
            set<int> st; st.insert(0);
            for (int p = 1; p <= m; ++p) {
                int tmp = vec[j][p] - vec[j][0] - vec[i][p] + vec[i][0];
                st.insert(tmp);
                ans = max(ans, tmp - *st.lower_bound(tmp - k));
            }
        }
    }

    cout << ans << "\n";

    return 0;
}