#include <iostream> using namespace std; int main() { int n, m; cin >> n >> m; int a[20][20]; int sum = 0; for (int i = 0; i < n; ++i) { for (int j = 0; j < m; ++j) { cin >> a[i][j]; if (i == 0 || i == n-1 || j == 0 || j == m-1) { sum += a[i][j]; } } } cout << sum<< endl; return 0; }