Treeinc

#include<stdio.h>
#include<vector>
using namespace std;
int dp[300010];
vector<int> adj[300010];

int cal(int u)
{
    if(dp[u])return dp[u];
    int cnt = 0;
    int maxtemp = 1;
    for(int i=0;i<adj[u].size();i++){
        int v = adj[u][i];
        if(v > u)
            maxtemp = max(maxtemp,cal(v) + 1);
    }
    return dp[u] = maxtemp;
}

int main(){
    int n;
    scanf("%d",&n);
    for(int i=1;i<n;i++){
        int u,v;
        scanf("%d %d",&u,&v);
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    int ans = -2e9;
    for(int i = 1; i<=n;i++){
        ans = max(ans,cal(i));
    }
    printf("%d",ans);
    return 0;
}