#include<cstdio>

 #include<cstdlib>

 #include<map>

 #include<set>

 #include<cstring>

 #include<algorithm>

 #include<vector>

 #include<cmath>

 #include<stack>

 #include<queue>

 #include<iostream>

 #define inf 0x7fffffff

 using namespace std;

 typedef long long LL;

 typedef pair<int, int> pr;

 int n;

 const int maxm = ;

 const int maxn = ;

 int g[maxn][maxn];

 //int head[maxn], to[maxm * 2], nxt[maxm * 2], vis[maxm * 2];

 int deg[maxn];

 int tot = ;

 stack<int>ans;

 void dfs(int now){

     for(int i = ; i <= ; i++){

         if(g[now][i] <= )continue;

         g[now][i]--;g[i][now]--;

         dfs(i);

     }

     ans.push(now);

     //printf("%c", now);

 }

 int main()

 {

     scanf("%d", &n);

     for(int i = ; i < n; i++){

         string s;

         cin>>s;

         g[s[]][s[]]++;g[s[]][s[]]++;

         //cout<<s[0]-'A'<<" "<<s[1]-'A'<<endl;

         deg[s[]]++;

         deg[s[]]++;

         //add(s[0] - 'A', s[1] - 'A');

     }

     //printf("%d\n", deg['I' - 'A']);

     int cnt = , dian = ;

     for(int i = ; i <= ; i++){

         if(deg[i] % ){

             cnt++;

             if(!dian)dian = i;

         }

     }

     if(!cnt){

         for(int i = ; i <= ; i++){

             if(deg[i]){

                 dian = i;

                 break;

             }

         }

     }

     if(cnt && cnt != ){

         printf("No Solution\n");

     }

     else{

         dfs(dian);

         //cout<<ans.size()<<endl;

         if(ans.size() >= n+){

             while(!ans.empty()){

                 printf("%c", ans.top());

                 ans.pop();

             }

             printf("\n");

         }

         else{

             printf("No Solution\n");

         }

     }

 }