1 #include<iostream> 
 2 #include<vector> 
 3 #include<string> 
 4 #include<algorithm> //reverse所在头文件 
 5 using namespace std;
 6     bool Comp(const string &str1,const string &str2)
 7     {
 8         if (str1.length()!=str2.length()) 
 9             return str1.length()<str2.length();
10         else
11             return str1<str2; 
12     }
13 int main() 
14 {
15     vector<string> n;
16     string s,t;
17     while(cin>>s) 
18     {
19         t=s; 
20         reverse(t.begin(),t.end());
21         if (t==s) 
22         {
23             n.push_back(s); 
24         }
25          
26     }
27     sort(n.begin(),n.end(),Comp);
28     for (vector<string>::iterator v=n.begin();v!=n.end();v++)
29     {
30         cout<<*v<<endl;
31     }
32 }