به نقل از صُبهان :
#include <algorithm>
#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <utility>
#include <string>
#include <vector>
#include <stack>
#include <deque>
#include <queue>
#include <set>
#include <map>
#include <cmath>
#include <ctime>
#include <cstdio>
#include <cstring>
using namespace std;
#define foreach(it,c) for (__typeof(c.begin()) it = c.begin(); it != c.end(); it++)
#define REP(i,N) for (int i = (0); i < (int)(N); i++)
typedef long long ll;
set <string> sa, sb;
vector <string> ans;
int main () {
string s;
getline (cin, s);
//cout << s.size () << endl;
REP (i,s.length())
for (int j=1; j<=s.length(); j++) {
string t = s.substr(i,j);
sa.insert( t );
}
reverse(s.begin(), s.end());
REP (i,s.length())
for (int j=1; j<=s.length(); j++) {
string t = s.substr(i,j);
sb.insert( t );
}
foreach (i,sa)
if (sb.find(*i) != sb.end())
ans.push_back(*i);
int res = 0;
REP (i,ans.size())
res = max(res, (int)ans[i].size());
cout << res << endl;
return 0;
}
