#include<iostream> using namespace std; int main(){ int n,m,a[15][15]; cin>>n>>m; int sum = 0; for(int i = 1;i <= n; ++i){ for(int j = 1;j <= m; ++j){ cin>>a[i][j]; sum += a[i][j]; } } for(int i = 2;i <= n - 1; i++){ for(int j = 2;j <= m - 1; j++){ sum -= a[i][j]; } } cout<<sum; return 0; }