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

int a[101][101];

int main() {
	int m, n;
	int he = 0;
	cin >> m >> n;
	for (int i = 0; i < m; i++) {
		for (int j = 0; j < n; j++) {
			cin >> a[i][j];
			if (i == 0) {
				he += a[i][j];
			}
			if (i == m - 1) {
				he += a[i][j];
			}
			if (j == 0) {
				he += a[i][j];
			}
			if (j == n - 1) {
				he += a[i][j];
			}
		}
	}


	he -= a[0][0];
	he -= a[0][n - 1];
	he -= a[m - 1][0];
	he -= a[m - 1][n - 1];

	cout << he;
	return 0;
}