#include<bits/stdc++.h>
using namespace std;
int n,m,a[1005][1005],p;
bool v[1005][1005];
int l=0,r=1000,ans=0;
int dx[4]={-1,1,0,0};
int dy[4]={0,0,-1,1};
struct node{
	int x,y;
};
bool bfs(int mid){
	memset(v,0,sizeof(v));
	queue<node> q;
	node start;
	start.x=1,start.y=1;
	q.push(start);
	v[1][1]=1;
	while(!q.empty()){
		node head=q.front();
		for(int i=0;i<=3;i++){
			int xx=head.x+dx[i];
			int yy=head.y+dy[i];
			if(xx>=1&&xx<=n&&yy>=1&&yy<=n&&!v[xx][yy]&&mid>=a[xx][yy]){
				if(xx==n)return 1;
				v[xx][yy]=1;
				node next;
				next.x=xx,next.y=yy;
				q.push(next);
			}
		}
		q.pop();
	}
}
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>a[i][j];
		}
	}
	while(l<=r){
		p=(l+r)>>1;
		if(bfs(p)) r=p-1,ans=p;
		else l=p+1;
	}
	cout<<ans;
	return 0;
}