代码

#include <iostream>
#include <string>

using namespace std;

int main()
{
    int n;
    while(cin >> n && n != 0)
    {
        string s[n];
        for(int i = 0; i < n; i ++)
        {
            cin >> s[i];
        }
        int res1 = 200;
        for(int i = 1; i < n; i ++)
        {
            int res2 = 0;
            for(int j = 1; j <= s[i].size(); j ++)
            {
                if(s[i][s[i].size() - j] == s[i - 1][s[i - 1].size() - j]) res2 ++;
            }
            if(res2 < res1) res1 = res2;
        }
        if(res1 == 0) cout << endl;
        else cout << s[0].substr(s[0].size() - res1, res1) << endl;
    }

    return 0;
}