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