#include<bits/stdc++.h> using namespace std; int main() { int n, m, a[15][15]; cin >> n >> m; int sum = 0; for (int i = 1; i <= n; ++i) { for (int j = 1; j <= m; ++j) { cin >> a[i][j]; sum += a[i][j]; } } for (int i = 2; i <= n - 1; i++) { for (int j = 2; j <= m - 1; j++) { sum -= a[i][j]; } } cout << sum; return 0; }