#include<bits/stdc++.h>
using namespace std;
int n,m,p[1401][1401];
bool vis[1401][1401],flag;
int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};
void dfs(int x,int y,int mid){
	if(x==n) flag=true;
	for(int i=0;i<4;i++){
		int xx=x+dx[i];
		int yy=y+dy[i];
		if(xx<=0||yy<=0||xx>n||yy>m||vis[xx][yy]||p[xx][yy]>mid) continue;
		vis[xx][yy]=true;
		dfs(xx,yy,mid);
		if(flag) return;
	}
}
int main(){
	int left,right;
	cin>>n>>m;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++){
			cin>>p[i][j];
			right=max(right,p[i][j]);
		}
	left=0;
	while(left<=right){
		memset(vis,false,sizeof(vis));
		flag=false;
		int mid=(left+right)>>1;
		dfs(1,1,mid);
		if(!flag) right=mid-1;
		else left=mid+1;
	} 
	cout<<left;
	return 0;
}

为什么输出的全是0