import java.io.*;

class Main{
    static StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
    static int nextInt()throws Exception{
        in.nextToken();
        return (int)in.nval;
    }

    static int R, C;
    static int[][] f, w;
    static int[] x = {0, 0, -1, 1};
    static int[] y = {1, -1, 0, 0};

    static int DP(int i, int j){
        if(f[i][j]>0) return f[i][j];

        for(int k=0; k<4; k++){
            if(j+x[k]>-1&&i+y[k]>-1&&i+y[k]<R&&j+x[k]<C&&w[i][j]>w[i+y[k]][j+x[k]])
                f[i][j] = Math.max(f[i][j], DP(i+y[k], j+x[k])+ 1); 
        }
        return f[i][j];
    }

    public static void main(String[] args)throws Exception{
        R = nextInt(); C = nextInt();
        f = new int[R][C];
        w = new int[R][C];
        for(int i=0; i<R; i++)
            for(int j=0; j<C; j++)
                w[i][j] = nextInt();
        int res = 0;
        for(int i=0; i<R; i++)
            for(int j=0; j<C; j++)
                res = Math.max(res, DP(i, j)+1);
        out.print(res);
        out.close();
    }
}