#include <cstdio> #include <cstdlib> #include <cstring> #include <algorithm> #include <cmath> #include <stack> #include <queue> #include <vector> #include <map> #include <string> #include <iostream> using namespace std; int father[1000]; int getfather(int x) { if(x!=father[x]) father[x]=getfather(father[x]); return father[x]; } void add(int a,int b) { int fa=getfather(a);int fb=getfather(b); if(fa!=fb) father[fa]=fb; } int vis[111111]; int out[100],in[1000]; bool ok() { int one=0;int two=0; int sum=0; for(int i=0;i<26;i++) if(vis[i]) if(father[i]==i) sum++; if(sum>1) return false; for(int i=0;i<26;i++){ if(in[i]-out[i]==1) one++; if(out[i]-in[i]==1) two++; if(out[i]==in[i]) continue; if(out[i]-in[i]>1||in[i]-out[i]>1) return false; } return ((one==1&&two==1)||(one==0&&two==0));// return one <= 1 && two <= 1 } int main() { int Icase;int n; int G[100][100]; char str[2000]; cin>>Icase; while(Icase--){ for(int i=0;i<26;i++) father[i]=i; cin>>n;int ans=0; memset(in,0,sizeof(in)); memset(out,0,sizeof(out)); memset(G,0,sizeof(G)); memset(vis,0,sizeof(vis)); for(int i=0;i<n;i++){ scanf("%s",str);int a=str[0]-'a';int len=strlen(str);int b=str[len-1]-'a'; add(a,b);in[b]++;out[a]++;vis[a]=1;vis[b]=1; } if(ok()) cout<<"Ordering is possible."<<endl; else cout<<"The door cannot be opened."<<endl; } return 0; }