#include<bits/stdc++.h>

using namespace std;

/// Typedef
typedef long long ll;

#define sc1(a) scanf("%lld",&a)
#define sc2(a,b) scanf("%lld %lld",&a,&b)

#define pf1(a) printf("%lld\n", a)
#define pf2(a,b) printf("%lld %lld\n",a,b)

#define mx 1000000
#define mod 1000000007
#define PI acos(-1.0)

#define size1 1000007

int drx[8] = {-2,-2,-1,-1,1,1,2,2};
int dcy[8] = {-1,1,-2,2,-2,2,-1,1};

int dirx[4] = { -1, 0, 1, 0 };
int diry[4] = { 0, -1, 0, 1 };


ll gcd(ll a,ll b){ if(b == 0) return a; return gcd(b, a % b); }
ll lcm(ll a,ll b){return a/gcd(a,b)*b;}

map <ll, ll> mp;
map <ll, ll> ::iterator it;
vector <pair<ll, ll> > vcp;

int main()
{

    ll tc, num, t = 1, pownum;

    //freopen("/opt/Coding/clion code/input.txt", "r", stdin);
    //freopen("/opt/Coding/clion code/output.txt", "w", stdout);

    while (cin >> num && num) {
        ll x, y;

        if(num == 1){
            cout << "YES" << endl;
            continue;
        }

        mp.clear(), vcp.clear();
        for(ll i = 0; i < num; i++) {

            sc2(x, y);
            mp[x]++;
            vcp.push_back(make_pair(x, y));
        }

        ll cnt = 0;
        for(ll i = 0; i < num; i++){
            mp[vcp[i].second]++;
        }

        bool check = true;
        for(it = mp.begin(); it != mp.end(); it++){
            ll now = it->second;
            if(now & 1){
                check = false;
                break;
            }
        }

        if(check == true) cout << "YES" << endl;
        else cout << "NO" << endl;
    }

    return 0;
}