#include <iostream>
#include <string>
#include <algorithm>
#include <map>
#include <vector>
#include <set>
#include <cstdlib>
#include <cstdio>
using namespace std;
const int maxn = 507;

vector<string> S;
map<string, int> idx;

vector<int> g[maxn];
bool used[maxn];
int tin[maxn], timer = 0;
int dfs(int v, int p = -1)
{
    tin[v] = timer++;
    used[v] = true;
    int res = 0;
    for (int i = 0; i < (int)g[v].size(); ++i)
    {
        int to = g[v][i];
        if (used[to])
        {
            res = max(res, tin[to] - tin[v]);
        }
        else
        {
            res = max(res, dfs(to));
        }
    }
    return res;
}

int main()
{
    //freopen("input.txt", "r", stdin);
    int n;
    cin >> n;
    vector<pair<string, string> > Q;
    for (int i = 0; i < n; ++i)
    {
        string a, b;
        cin >> a >> b;
        Q.push_back(make_pair(a, b));
        S.push_back(a);
        S.push_back(b);
    }
    sort(S.begin(), S.end());
    S.resize(distance(S.begin(), unique(S.begin(), S.end())));

    for (int i = 0; i < (int)S.size(); ++i)
    {
        idx[S[i]] = i;
    }

    for (int i = 0; i < n; ++i)
    {
        int a = idx[Q[i].first],
            b = idx[Q[i].second];
        g[a].push_back(b);
        g[b].push_back(a);
    }

    int ans = 0;
    for (int i = 0; i < (int)S.size(); ++i)
    {
        if (!used[i])
        {
            ans = max(ans, dfs(i));
        }

    }
    if (ans < 3)
        cout << 0;
    else
        cout << ans;

    return 0;
}