SA

//   __________________
//  | ________________ |
//  ||          ____  ||
//  ||   /\    |      ||
//  ||  /__\   |      ||
//  || /    \  |____  ||
//  ||________________||
//  |__________________|
//  \###################\
//   \###################\
//    \        ____       \
//     \_______\___\_______\
// An AC a day keeps the doctor away.

#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector")
#pragma loop_opt(on)
#include <bits/extc++.h>
#ifdef local
#define debug(x) (cerr<<#x<<" = "<<(x)<<'\n')
#else
#define debug(x) ((void)0)
#endif // local
#define all(v) begin(v),end(v)
#define siz(v) (ll(v.size()))
#define get_pos(v,x) (lower_bound(all(v),x)-begin(v))
#define sort_uni(v) sort(begin(v),end(v)),v.erase(unique(begin(v),end(v)),end(v))
#define pb emplace_back
#define ff first
#define ss second
#define mid (l+(r-l>>1))
#define mem(v,x) memset(v,x,sizeof v)

using namespace std;
using namespace __gnu_pbds;
typedef int64_t ll;
typedef long double ld;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pld;
template <typename T> using max_heap = __gnu_pbds::priority_queue<T,less<T> >;
template <typename T> using min_heap = __gnu_pbds::priority_queue<T,greater<T> >;
template <typename T> using rbt = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
constexpr ld PI = acos(-1), eps = 1e-9;
constexpr ll N = 100025, INF = 1e18, MOD = 20191126, K = 4, inf = 1e9;
constexpr ll modpow(ll e,ll p,ll m=MOD) {ll r=1; for(;p;p>>=1,e=e*e%m) if(p&1) r=r*e%m; return r;}
constexpr inline ll cdiv(ll x, ll m) { return (x+m-1)/m; } // ceiling divide, x/m for flooring divide
template <typename T> void M(T &x, ll m=MOD){x%=m; if(x<0) x+=m;}

string s;
struct SuffixArray {
    int sa[N],rk[N],tmp[N],n,LCP[N];
    void solve(const string &s) {
        n = s.size();
        iota(sa,sa+n,0);
        for(int i = 0; i < n; i++) rk[i] = s[i];
        for(int L = 1; L < n; L *= 2) { // sort by the prefix [0:L]
            auto cmp = [&](int a,int b){
                if(rk[a] != rk[b]) return rk[a]<rk[b];
                int ra = (a+L<n ? rk[a+L] : -1);
                int rb = (b+L<n ? rk[b+L] : -1);
                return ra<rb;
            };
            sort(sa,sa+n,cmp);
            tmp[sa[0]] = 0;
            for(int i = 1; i < n; i++) tmp[sa[i]] = (tmp[sa[i-1]]+cmp(sa[i-1],sa[i]));
            for(int i = 0; i < n; i++) rk[i] = tmp[i];
        }
        for(int i = 0; i < n; i++) sa[rk[i]] = i;
        //for(int i = 0; i < n; i++) cout << s.substr(sa[i], n-sa[i]) << '\n';
        //return;
        for(int i = 0, j, h=0; i < n; i++) {
            if(rk[i] == 0) continue;
            if(h > 0) --h;
            for(int j = sa[rk[i]-1]; i+h < n && j+h < n && s[i+h]==s[j+h]; h++);
            LCP[rk[i]] = h;
        }
        int i = max_element(LCP,LCP+n)-LCP;
        cout << s.substr(sa[i], LCP[i]) << '\n';
    }
} SA;
signed main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    cin >> s;
    SA.solve(s);
}