HustOJ - 1020

#include<iostream> 
#include<vector> 
#include<string> 
#include<algorithm> //reverse所在头文件 
using namespace std;
    bool Comp(const string &str1,const string &str2)
    {
        if (str1.length()!=str2.length()) 
            return str1.length()<str2.length();
        else
            return str1<str2; 
    }
int main() 
{
    vector<string> n;
    string s,t;
    while(cin>>s) 
    {
        t=s; 
        reverse(t.begin(),t.end());
        if (t==s) 
        {
            n.push_back(s); 
        }
         
    }
    sort(n.begin(),n.end(),Comp);
    for (vector<string>::iterator v=n.begin();v!=n.end();v++)
    {
        cout<<*v<<endl;
    }
}