非常简单，优势在我！！！

#include<bits/stdc++.h>
#define int long long
using namespace std;
constexpr int N=1e5+10;
int n,m,k;
map<pair<int,int>,int>mp;
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	while(cin>>n>>m){
		mp.clear();k=0;
		for(int i=1;i<=m;i++){
			int x,y;
			cin>>x>>y;
			if(x>y)swap(x,y);
			if(!mp[{x,y}]++)k++;
		}
		for(int i=1;i<=m;i++){
			int x,y;
			cin>>x>>y;
			if(x>y)swap(x,y);
			if(!--mp[{x,y}])k--;
		}
		cout<<(!k?"YES":"NO")<<"\n";
	}
}

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

bool solve(int n,int m)
{
    vector<int> a(m), b(m);
    for (int i = 0; i < m; i++) cin >> a[i] >> b[i];
    vector<int> c(m), d(m);
    for (int i = 0; i < m; i++) cin >> c[i] >> d[i];
    
    map< pair<int, int> , vector<int> > edge_to_id;
    for (int j = 0; j < m; j++) {
        edge_to_id[{min(a[j], b[j]), max(a[j], b[j])}].push_back(j);
    }
    
    vector<bool> used(m, false);
    
    for (int i = 0; i < m; i++) {
        pair<int, int> tno = {min(c[i], d[i]), max(c[i], d[i])};
        if (edge_to_id[tno].empty()) return 0;

        bool flg = false;
        for (int j : edge_to_id[tno]) {
            if (!used[j] && ((c[i] == a[j] && d[i] == b[j]) || (c[i] == b[j] && d[i] == a[j]))) {
                used[j] = true;
                flg = true;
                break;
            }
        }
        if (!flg) return 0;
    }
    
    for (int i = 0; i < m; i++) if (!used[i]) return 0;
    
    return 1;
}

int main() {
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    int n, m;
    while(cin >> n >> m){
	  if(solve(n,m)) cout << "YES\n";
	  else cout << "NO\n";
    }
	return 0;
}