import java.util.Scanner;
public class Main{
    static int n;
    static int m;
    static int flag;
    static int mid;
    static int N = 1010;
    static int a[][] = new int[N][N];
    static int vis[][] = new int[N][N];
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        m = sc.nextInt();
        int res = 0;
        for(int i = 1;i <= n;i++){
            for(int j = 1;j <= m;j++){
                a[i][j] = sc.nextInt();
                res = Math.max(res,a[i][j]);
            }
        }
        int l = 0,r = res - 1;
        while(l + 1 != r){
            mid = l + r >>1;
            flag = 0;
            dfs(1,1,mid);
            if(flag == 1){
                r = mid;
            }
            else l = mid;
        }
        System.out.println(r);
    }

    public static void dfs(int x,int y,int mid){
        if(x == n){
            flag = 1;
        }
        int d[][] = new int[][]{{0,-1},{-1,0},{0,1},{1,0}};
        for(int i = 0;i < 4;i++){
            int xx = x + d[i][0];
            int yy = y + d[i][1];
            if(xx >= 1 && yy >= 1 && xx <= n && yy <= m){
                if(vis[xx][yy] == 0 && a[xx][yy] <= mid){
                    vis[xx][yy] = 1;
                    dfs(xx,yy,mid);
                    vis[xx][yy] = 0;
                    if(flag == 1) break;
                }
            }
        }
    }
}