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