#include <bits/stdc++.h>
using namespace std;
int B[111][111];
int A[111][111];
int R, C;
stack<pair<int, int>> st;
int calc(int ni, int nj, int di, int dj) {
	ni += di; nj += dj;
	int ret = 0;
	while (true) {
		if (ni <= 0 || ni > R || nj <= 0 || nj > C) break;
		if (B[ni][nj] <= 0) break;
		ret += B[ni][nj];
		B[ni][nj] = 0;
		st.emplace(ni, nj);
		ni += di; nj += dj;
	}
	return ret;
}
void fuku() {
	while (!st.empty()) {
		auto [i, j] = st.top();
		st.pop();
		B[i][j] = A[i][j];
	}
}
int main() {
	cin >> R >> C;
	for (auto& a : A) {
		fill(a, a + (C + 10), 0);
	}
	for (int i = 1; i <= R; i ++) {
		for (int j = 1; j <= C; j ++) {
			cin >> A[i][j];
		}
	}
	for (int i = 0; i <= R + 1; i ++) {
		for (int j = 0; j <= C + 1; j ++) {
			B[i][j] = A[i][j];
		}
	}
	int ans = 0;
	for (int i1 = 0; i1 <= R + 1; i1 ++) {
		for (int j1 = 0; j1 <= C + 1; j1 ++) {
			if (0 < i1 && i1 <= R && 0 < j1 && j1 <= C) continue;
			for (int di = -1; di < 2; di ++) {
				for (int dj = -1; dj < 2; dj ++) {
					if (di == 0 && dj == 0) continue;
					for (int i2 = 0; i2 <= R + 1; i2 ++) {
						for (int j2 = 0; j2 <= C + 1; j2 ++) {
							if (0 < i2 && i2 <= R && 0 < j2 && j2 <= C) continue;
							for (int di2 = -1; di2 < 2; di2 ++) {
								for (int dj2 = -1; dj2 < 2; dj2 ++) {
									if (di2 == 0 && dj2 == 0) continue;
									ans = max(ans, calc(i1, j1, di, dj) + calc(i2, j2, di2, dj2));
									fuku();
								}
							}
						}
					}
				}
			}
		}
	}
	cout << ans << endl;
}