#include<bits/stdc++.h>
using namespace std;
int read() {
	int s = 0, w = 1;
	char c = getchar();
	while (c < '0' || c > '9') {
		if (c == '-') w = -1;
		c = getchar();
	}
	while (c >= '0' && c <= '9') { 
		s = s * 10 + c - '0';
		c = getchar();
	}
	return s * w;
}
void print(int x) {
	if (x < 0) { //判负
		putchar('-');
		x = -x;
	}
	if (x >= 10)
		print(x / 10);
	putchar(x % 10 + '0');
	return;
}
#define fro(n) for(int i=1;i<=n;i++)
#define ofr(n) for(int i=1;i<=n;i++)
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
const double eps = 1e-6;
const int maxn = 1e8;
const int mod = 1e6+7;
const int INF = 0x3f3f3f3f;
const int maxsize = 105;
LL dp[maxsize][maxsize];
struct node{
	LL x,y;
	LL value;
	friend bool operator < (node x,node y){
		return x.value > y.value;
	}
}a[maxsize][maxsize];
priority_queue <node> p;

void solve();
bool check(int x);
void dfs(int x,int y);
bool cmp(node x,node y);
int main(){
	//freopen("001.in","r",stdin);
	//freopen("001.out","w",stdout);
	LL T = 1;
	//scanf("%d",&T);
	while(T--){
		LL ans = 0;
		int n = read(),m= read();
		for(int i = 1;i <= n;i++){
			for(int j = 1;j <= m;j++){
				a[i][j].value = read();
				a[i][j].x = i;
				a[i][j].y = j;
				p.push(a[i][j]);
			}
		}
		while(!p.empty()){
				node start = p.top();
				if(a[start.x][start.y].value > a[start.x - 1][start.y].value){
					dp[start.x][start.y] = max(dp[start.x][start.y],dp[start.x - 1][start.y] + 1);
				}
				if(a[start.x][start.y].value > a[start.x + 1][start.y].value){
					dp[start.x][start.y] = max(dp[start.x][start.y],dp[start.x + 1][start.y] + 1);
				}
				if(a[start.x][start.y].value > a[start.x][start.y - 1].value){
					dp[start.x][start.y] = max(dp[start.x][start.y],dp[start.x][start.y - 1] + 1);
				}
				if(a[start.x][start.y].value > a[start.x][start.y + 1].value){
					dp[start.x][start.y] = max(dp[start.x][start.y],dp[start.x][start.y + 1] + 1);
				}
				ans = max(ans,dp[start.x][start.y]);
				p.pop();
		//		cout << start.x << " " << start.y << " " << dp[start.x][start.y] << endl;
		}
		print(ans);
	}
	return 0;
}

提交记录，题目P1434。