#include<iostream>
#include<vector>
using namespace std;

struct node {
    vector<int> son;
};

int n, ans;

bool used[10009];

node tree[10009];

void dfs(int x, int y, bool u[]);

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        int u, v;
        cin >> u >> v;
        used[u] = used[v] = 1;
        tree[u].son.push_back(v);
    }
    dfs(1, 0, used);
    cout << ans << endl;
    return 0;
}

void dfs(int x, int y, bool u[]) {
    u[x] = 0;
    ans = max(ans, y);
    for (int i = 0; i < tree[x].son.size(); i++) {
        if (u[tree[x].son[i]]) dfs(tree[x].son[i], y + 1, u);
    }
}