//pB
#include<bits/stdc++.h>
using namespace std;
#define LL long long
#define pii pair<int, int>
#define S second
#define F first
const int maxn = 3e5 + 10;
const int inf = 1e9;
int n, m, k;
vector<int> ban[maxn], v[maxn];
int cnt[maxn];
vector<pii> ans;
int vis[maxn];
int f1=-1, t1=-1, f2=-1, t2=-1;
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n>>m>>k;
if(n<=k){
// cout<<n<<" "<<k;
cout<<"NO";
return 0;
}
while(m--){
int a, b; cin>>a>>b;
v[a].push_back(b);
ans.push_back({a, b});
}
int kk=k;
while(kk--){
int a, b; cin>>a>>b;
ban[a].push_back(b);
cnt[a]++;
if(f1==-1) f1=a, t1=b;
else f2=a, t2=b;
}
// cout<<f1<<" "<<t1<<" "<<f2<<" "<<t2<<"\n";
if(k==0){
for(int i=1; i<n; i++) cout<<i-1<<" "<<i<<"\n";
}else if(k==1){
//cout<<"YES";
for(int i=0; i<n; i++)
if(i!=f1) cout<<i<<" "<<f1<<"\n";
}else if(k==2){
int x=-1;
for(int i=0; i<n; i++)
if(i!=t1 and i!=t2){
x=i; break;
}
if(x==-1){
cout<<"NO";
return 0;
}
for(int i=0; i<n; i++)
if(i!=x) cout<<i<<" "<<x<<"\n";
}
}
