UVA 1610

#include <bits/stdc++.h>using namespace std;const int maxn = 1E3 + 10;int n, k;string inp[maxn];int main(int argc, char const *argv[]){while (cin >> n && n){for (int i = 0; i < n; i++)cin >> inp[i];sort(inp, inp + n);string s1 = inp[n / 2 - 1], s2 = inp[n / 2], ans;for (k = 0; s1[k] == s2[k]; k++)ans += s1[k];while (!(ans >= s1 && ans < s2)){for (char i = 'A'; i <= 'Z'; i++)if (ans + i >= s1 && ans + i < s2){ans += i;break;}if (!(ans >= s1 && ans < s2))ans += s1[k++];}cout << ans << endl;}return 0;}