#include"stdio.h"
int map[102][102],result[102][102],tall,wide,max,sec[4][2]={-1,0,1,0,0,-1,0,1};
void cal(int x,int y){
    int a,b,i;
    for(i=0;i<4;i++){
        a=x+sec[i][0];
        b=y+sec[i][1];//&Eacute;è×&oslash;±ê 
        if(map[a][b]<map[x][y]&&result[a][b]<result[x][y]+1){
                   result[a][b]=result[x][y]+1;
                   if(max<result[a][b])max=result[a][b];
                   cal(a,b);
         }
    }
}

int main(){
    int i,j,big_x,big_y,big;
    scanf("%d %d",&tall,&wide);
    
    for(i=1;i<=tall;i++){
        for(j=1;j<=wide;j++){
                scanf("%d",&map[i][j]);
                result[i][j]=0;
        }
    }//first
    for(i=0;i<=tall+1;i++){
        map[i][0]=10001;map[i][wide+1]=10001;
    }
    for(i=0;i<=wide+1;i++){
        map[0][i]=10001;map[tall+1][i]=10001;
    }
    max=1;
while(1){
    big=-1;
    for(i=1;i<=tall;i++)
        for(j=1;j<=wide;j++)
             if(result[i][j]==0&&map[i][j]>=big){
                    big_x=i;
                    big_y=j; 
                    big=map[i][j];
             }
    
    if(big==-1)break;
    result[big_x][big_y]=1;
    cal(big_x,big_y);
}//while      
    printf("%d\n",max);
    return 0;
}