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#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define ROF(i, a, b) for (int i = (a); i >= (b); --i)
#define all(x) x.begin(),x.end()
#define CLR(i,a) memset(i,a,sizeof(i))
#define fi first
#define se second
#define pb push_back
#define SZ(a) ((int) a.size())
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef array<ll,3> arr;
typedef double DB;
typedef pair<DB,DB> pdd;
typedef pair<ll,bool> plb;
constexpr ll MAXN=static_cast<ll>(5e5)+10,INF=static_cast<ll>(5e18)+3;
constexpr ll base=131;
ll N,M,T,A[MAXN];
ull hashe[MAXN],hashrs[MAXN];
ull powBase[MAXN];
inline void solve(){
string s;
cin>>s;
string rs(s.rbegin(),s.rend());
rs='0'+rs;
N=SZ(s);
if(N==1){
cout<<s<<"\n";
return;
}
powBase[0]=1;
FOR(i,1,N){
powBase[i]=powBase[i-1]*base;
}
s='0'+s;
FOR(i,1,N){
hashe[i]=hashe[i-1]*base+s[i];
}
FOR(i,1,N){
hashrs[i]=hashrs[i-1]*base+rs[i];
}
FOR(i,N/2+1,N){
ull len,suf,pre;
len=N-i+1;
suf=hashrs[len]-hashrs[0]*powBase[len];
pre=hashe[i-1]-hashe[i-len-1]*powBase[len];
if(suf==pre){
FOR(i,1,N){
cout<<s[i];
}
FOR(i,len*2+1,N){
cout<<rs[i];
}
cout<<"\n";
return;
}
len=N-i;
suf=hashrs[len]-hashrs[0]*powBase[len];
pre=hashe[i-1]-hashe[i-len-1]*powBase[len];
if(suf==pre){
FOR(i,1,N){
cout<<s[i];
}
FOR(i,len*2+2,N){
cout<<rs[i];
}
cout<<"\n";
return;
}
}
FOR(i,1,N){
cout<<s[i];
}
FOR(i,1,N){
cout<<rs[i];
}
cout<<"\n";
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
solve();
return 0;
}
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