#include <bits/stdc++.h>
using namespace std;
#define For(Ti,Ta,Tb) for(auto Ti=(Ta);Ti<=(Tb);++Ti)
#define Dec(Ti,Ta,Tb) for(auto Ti=(Ta);Ti>=(Tb);--Ti)
#define debug(...) fprintf(stderr,__VA_ARGS__)
#define range(Tx) begin(Tx),end(Tx)
using ll=long long;
const int N=205;
int n,m,b[N][N],ans;
void work(int i){
	if(m%3==0){
		for(int j=2;j<=m;j+=3){
			ans+=b[i][j];
		}
	}else if(m%3==1){
		ans+=b[i][1]+b[i][m];
		for(int j=4;j<=m-2;j+=3){
			ans+=b[i][j];
		}
	}else{
		ans+=b[i][1];
		for(int j=4;j<=m;j+=3){
			ans+=b[i][j];
		}
	}
}
int main(){
	cin.tie(nullptr)->sync_with_stdio(false);
	cin>>n>>m;
	For(i,1,n){
		For(j,1,m){
			cin>>b[i][j];
		}
	}
	if(n%3==0){
		for(int i=2;i<=n;i+=3){
			work(i);
		}
	}else if(n%3==1){
		work(1);
		work(n);
		for(int i=4;i<=n-2;i+=3){
			work(i);
		}
	}else{
		work(1);
		for(int i=4;i<=n;i+=3){
			work(i);
		}
	}
	cout<<ans<<'\n';
	return 0;
}