#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 j = 0; j < n; ++j) s = s + a[0][j]; for(int j = 0; j < n; ++j) s = s + a[m - 1][j]; for(int i = 0; i < m; ++i) s = s + a[i][0]; for(int i = 0; i < m; ++i) s = s + a[i][n - 1]; s = s - a[0][0] - a[0][n - 1] - a[m - 1][0] - a[m - 1][n - 1]; cout << s << '\n'; return 0; }