#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <vector>
#include <queue>
#include <iostream>
#include <cassert>
#include <bitset>
#include <ctime>

using namespace std;

typedef long long LL;
typedef double DB;
typedef pair<int, int> PII;
typedef vector<int> VI;

#define X first
#define Y second
#define pb push_back

template<class T>
inline void chkmin(T &x, T y) {
    if (y < x) x = y;
}

template<class T>
inline void chkmax(T &x, T y) {
    if (x < y) x = y;
}

const int MN = 1005;
int n;
int f[MN], vis[MN], sz, cyc[MN], T;
VI con[MN];
VI V;
int p1, p2;
int pr[MN];
int bf;

void dfs(int u, int p) {
    int i, v;
    
    sz++;
    pr[u] = p;
    vis[u] = T;
    for (i = con[u].size() - 1; i >= 0; i--) {
        v = con[u][i];
        if (vis[v] == T) {
            if (v != p) {
                if (!bf) {
                    p1 = u;
                    p2 = v;
                    bf = 1;
                }
            }
            continue;
        }
        dfs(v, u);
    }
}

bool ddfs(int u) {
    int i, v, cnt(0);
    
    vis[u] = T;
    for (i = con[u].size() - 1; i >= 0; i--) {
        v = con[u][i];
        if (vis[v] == T) continue;
        if (v == V[0]) continue;
        cnt++;
        if (!ddfs(v)) return 0;    
    }
    if (cnt >= 2) return 0;
    
    return 1;
}

bool DFS(int u, int p) {
    int i, v, cnt(0);
    
    sz++;
    for (i = con[u].size() - 1; i >= 0; i--) {
        v = con[u][i];
        if (cyc[v] == T) continue;
        if (v == p) continue;
        cnt++;
        if (!DFS(v, u)) return 0;    
    }
    if (cnt >= 2) return 0;
    
    return 1;
}

int chk[MN][MN], VT;

int main() {
    
//    freopen("in.txt", "r", stdin);
//    freopen("out.txt", "w", stdout);
    
    int i, j, k, tn;
    
    while (scanf("%d", &n) == 1) {
        memset(f, 0, sizeof f);
        memset(vis, 0, sizeof vis);
        memset(cyc, 0, sizeof cyc);
        T = 0;
        
        for (i = 0; i < n; i++) con[i].clear();
        VT++;
        int flag(0);
        for (i = 0; i < n; i++) {
            scanf("%d%d", &j, &k);
            j--, k--;
            con[j].pb(k);
            con[k].pb(j);
            if (chk[j][k] == VT) {
                p1 = j;
                p2 = k;
                flag = 1;
            }
            chk[j][k] = chk[k][j] = VT;
            f[j] = k;
        }
        sz = 0;
        T++;
        bf = 0;
        dfs(0, -1);
        if (sz != n) {
            puts("NO");
            continue;    
        }
        
            V.clear();
         if (!flag) {
            int u;
            T++;
            for (u = p1; u != p2; u = pr[u]) V.pb(u), cyc[u] = T;
            V.pb(p2), cyc[p2] = T;
        } else {
            T++;
            V.pb(p1);
            V.pb(p2);
            cyc[p1] = T;
            cyc[p2] = T;    
        }
        if (V.size() > 1) {
            int cnt(0);
            int a[5];
            for (i = 0; i < V.size(); i++) {
                sz = 0;
                if (!DFS(V[i], -1)) break;
                if (sz > 1) {
                    a[cnt++] = V[i];
                }
            }
            if (i < V.size()) {
                puts("NO");
                continue;    
            }
            if (cnt == 2 && chk[a[0]][a[1]] != VT) {
                puts("NO");
                continue;
            }
            printf("%s\n", cnt <= 2 ? "YES" : "NO");
            continue;
        }
        int cnt = 0;
        for (i = 0; i < con[V[0]].size(); i++) {
            int v = con[V[0]][i];
            if (v == V[0]) continue;
            cnt++;
        }
        if (cnt > 2) {
            puts("NO");
            continue;    
        }
        for (i = 0; i < con[V[0]].size(); i++) {
            int v = con[V[0]][i];
            if (v == V[0]) continue;
            T++;
            if (!ddfs(v)) break;
        }
        if (i < con[V[0]].size()) {
            puts("NO");
            continue;    
        }
        puts("YES");
    }
    
    return 0;    
}