int main(int argc, char const *argv[])
{
    string s;
    cin>>s;
    string t=s;
    reverse(all(t));
    string a=t+'#'+s;
    //cout<<a<<"\n";
    int n=sz(a);
    vector<int> p(n);
    int i=1,j=0;
    p[0]=0;
    for(int i=1;i<n;){
    //  cout<<i<<" "<<j<<"\n";
        if(a[i]==a[j]){
            p[i]=j+1;
            ++i;
            ++j;
        }
        else{
            if(j>0)j=p[j-1];
            else{
                p[i]=0;
                ++i;
            }
        }
    }
    int l=sz(s)-p[n-1];
    //cout<<p[n-1]<<"\n";
    cout<<s;
    int  co=0;
    while(co<l){
        cout<<s[l-co-1];
        ++co;
    }
    cout<<"\n";
    return 0;
}