#include<cstdio>

 #include<cstring>

 #include<algorithm>

 #include<set>

 using namespace std;

 const int N = 1e3 + ;

 int n, up = 'z' - 'A' + ;

 int ans[N], tot, d[N], num;

 multiset<int> to[N];

 void dfs(int u) {

     multiset<int> :: iterator i;

     for (i = to[u].begin(); i != to[u].end(); i = to[u].begin()) {

         int nt = *i;

         to[nt].erase(to[nt].find(u));

         to[u].erase(to[u].find(nt));

         dfs(nt);

     }

     ans[++tot] = u;

 }

 int main()

 {

     scanf("%d", &n);

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

         char s[];

         scanf("%s", s);

         to[s[] - 'A' + ].insert(s[] - 'A' + );

         to[s[] - 'A' + ].insert(s[] - 'A' + );

         d[s[] - 'A' + ]++;

         d[s[] - 'A' + ]++;

     }

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

         if (d[i] & )

             num++;

     if (num ==  || num > )

         return puts("No Solution"), ;

     if (num == ) {

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

             if (d[i]) {dfs(i); break;}

     }

     else

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

             if (d[i] && (d[i] & )) {dfs(i); break;}

     for (int i = tot; i; i--)

         putchar(ans[i] + 'A' - );

     puts("");

 }