lobinhos

#include <bits/stdc++.h>
using namespace std;

#define INF 1000000000
#define mp make_pair
#define pb push_back
#define st first
#define nd second
#define FOR(i,a,b) for(int (i) = (a); (i) < (b); (i)++)
#define sz(X) (int)(X).size()
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<int> vi;

int main(){
    int n;
    int ans = 0;
    cin >> n;
    vii votos;
    FOR(i,0,n){
        int a, b;
        scanf("%d%d", &a, &b);
        votos.pb(mp(a-1,b-1));
    }

    FOR(lobo, 0, n){
        int v_lobo = 0;
        set<int> votaram;
        votaram.insert(lobo);
        FOR(i,0,n){
            if(i == lobo) continue;
            ii curr = votos[i];
            if(curr.st == lobo || curr.nd == lobo){
                v_lobo++;
                votaram.insert(i);
            }
        }
        set<int> to_vote;
        FOR(i,0,n){
            if(votaram.count(i) == 0) to_vote.insert(i);
        }
        vi hp(n, v_lobo);
        hp[lobo] = 0;
        hp[votos[lobo].st]--;
        hp[votos[lobo].nd]--;

        if(hp[votos[lobo].st] <= 0 || hp[votos[lobo].nd] <= 0){
            ans++;
            continue;
        }

        vector<bool> safe(n, false);

        safe[lobo] = true;

        while(true){
            vi freq(n, 0);
            for(int i : to_vote){
                ii curr = votos[i];
                freq[curr.st]++;
                freq[curr.nd]++;
            }

            int mini = INF, minind = -1;
            FOR(i,0,n){
                if(safe[i]) continue;
                if(freq[i] < hp[i]){
                    if(freq[i] < mini){
                        mini = freq[i];
                        minind = i;
                    }
                }
            }

            if(mini == INF) break;

            set<int> to_erase;

            for(int i: to_vote){
                ii curr = votos[i];
                if(curr.st == minind || curr.nd == minind){
                    to_erase.insert(i);
                }
            }
            for(int i: to_erase){
                to_vote.erase(i);
                hp[minind]--;
            }
            safe[minind] = true;
        }

        for(int i : hp){
            //cout << i << " ";
        }
        //cout << endl;

        if(sz(to_vote) == 0) continue;

        int sobra = sz(to_vote);
        int not_safe_hp = 0;
        FOR(i,0,n){
            if(!safe[i]) not_safe_hp+=(hp[i]-1);
        }

        if(sobra > not_safe_hp){
            ans++;
        }
    }

    cout << ans << endl;

    return 0;
}