保证过

#include <bits/stdc++.h>
using namespace std;
int n , m;
int main(){
	cin >> m >> n;
	int a[210][210] = {0};
	int dp[210][210] = {0};
	for(int i = 0 ; i < m ; i++){
		for(int j = 0 ; j < n ; j++){
			cin >> a[i][j];
		}
	}
	int mid = n / 2;
	for(int j = 0 ; j < n ; j++){
		if(j == mid - 1 || j == mid || j == mid + 1){
			dp[m - 1][j] = a[m - 1][j];
		}
		else{
			dp[m - 1][j] = -1e9;
		}
	}
	for(int i = m - 2 ; i >= 0 ; i--){
		for(int j = 0 ; j < n ; j++){
			int left = (j > 0) ? dp[i + 1][j - 1] : -1e9;
			int center = dp[i + 1][j];
			int right = (j < n - 1) ? dp[i + 1][j + 1] : -1e9;
			dp[i][j] = max({left , center , right}) + a[i][j];
		}
	}
	int ans = -1e9;
	for(int j = 0 ; j < n ; j++){
		if(dp[0][j] > ans){
			ans = dp[0][j];
		}
	}
	cout << ans << endl;
	return 0;
}