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