int n;
        cin>>n;

        vector<vector<int>> g(n);
        vector<int> deg(n);
        for(int i=0, u, v; i<n-1; i++){
            cin>>u>>v;
            --u, --v;
            g[u].pb(v);
            g[v].pb(u);
            ++deg[u], ++deg[v];
        }

        int ans = 1;
        auto dfs = [&](auto self, int v, int p = -1) -> int {
            int mx1 = 0, mx2 = 0;
            for(auto &c : g[v]){
                if(c == p) continue;
                int res = self(self,c,v);
                if(res > mx1) mx2 = mx1, mx1 = res;
                else mx2 = max(mx2, res);
            }
            ans = max(ans, mx1+mx2-(mx1>0)-(mx2>0)+deg[v]);
            return (mx1-(mx1>0)+deg[v]-1);
        };

        dfs(dfs,0);
        cout<<ans<<nl;

int n;
        cin>>n;

        vector<int> g[n];
        vector<int> deg(n);
        for(int i=0, u, v; i<n-1; i++){
            cin>>u>>v;
            --u, --v;
            g[u].pb(v);
            g[v].pb(u);
            ++deg[u], ++deg[v];
        }

        int ans = 1;
        auto dfs = [&](auto self, int v, int p = -1) -> int {
            int mx1 = 0, mx2 = 0;
            for(auto &c : g[v]){
                if(c == p) continue;
                int res = self(self,c,v);
                if(res > mx1) mx2 = mx1, mx1 = res;
                else mx2 = max(mx2, res);
            }
            ans = max(ans, mx1+mx2-(mx1>0)-(mx2>0)+deg[v]);
            return (mx1-(mx1>0)+deg[v]-1);
        };

        dfs(dfs,0);
        cout<<ans<<nl;