#include <iostream>
#include <cstring>
#include <vector>

using namespace std;

int main()
{
    char str[20000],str2[10000],str3[10000];
    unsigned int len;
    unsigned int i,j,k;
    vector<char>check;
    char ch;

    while(gets(str))
    {
        len=strlen(str);

        if(len==1)
            cout<<str[0]<<str[0]<<endl;

        else
        {

            for(i=0;i<len;i++)
                str2[i]=str[len-1-i];

            if(strncmp(str,str2,len)==0)
            {
                for(i=1;i<=len;i++)
                {
                    for(j=i;j<len;j++)
                    {
                        ch=str[j];
                        check.push_back(ch);
                    }

                    for(j=0;j<check.size();j++)
                    {
                        str2[j]=check[j];
                        str3[j]=check[check.size()-1-j];
                    }

                    if(strncmp(str2,str3,check.size())==0)
                    {
                        for(k=0;k<i;k++)
                            str[len+k]=str[i-k-1];

                        for(k=0;k<len+i;k++)
                            cout<<str[k];
                        cout<<endl;

                        check.clear();
                        break;
                    }
                    check.clear();
                }
            }

            else
            {
                for(i=0;i<len;i++)
                {
                    for(j=i;j<len;j++)
                    {
                        ch=str[j];
                        check.push_back(ch);
                    }

                    for(j=0;j<check.size();j++)
                    {
                        str2[j]=check[j];
                        str3[j]=check[check.size()-1-j];
                    }

                    if(strncmp(str2,str3,check.size())==0)
                    {
                        for(k=0;k<i;k++)
                            str[len+k]=str[i-k-1];

                        for(k=0;k<len+i;k++)
                            cout<<str[k];
                        cout<<endl;

                        check.clear();
                    break;
                    }
                    check.clear();
                }
            }
        }

    }

    return 0;
}

My freind i not c++ but I do at java and AC 0.265
My main function code that


while(true){
            if(n+1==k-n1)if(ch[n]==ch[k-n1])break;
            if(n==k-n1)break;
            if(ch[n]==ch[k-n1]){
                n++;
                n1++;
            }
            else{
                k1++;
                n=k1;
                n1=1;
            }
        }