#include<iostream> using namespace std; int a[21][21]; int main(){ int n,m,sum=0; cin>>n>>m; 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; }