#include<iostream>
#include<cstdio>
#include<map>
#include<cstdlib>
#include<random>
#define N 2000000
#define M 25000000
#define K 16777215
#define Base1 131
#define Base2 171
#define mod1 998244353
#define mod2 998244853
using namespace std;
mt19937 RAND(random_device{}());
int read()
{
	char c=0;
	int sum=0;
	while (c<'0'||c>'9') c=getchar();
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum;
}
int MD1(int x)
{
	return x>=mod1?x-mod1:x;
}
int MD2(int x)
{
	return x<0?x+mod1:x;
}
int MD3(int x)
{
	return x>=mod2?x-mod2:x;
}
int MD4(int x)
{
	return x<0?x+mod2:x;
}
struct reads
{
	int hsh1,hsh2;
	bool operator == (const reads &t)const
	{
		return hsh1==t.hsh1&&hsh2==t.hsh2;	
	}
};
reads rd[26],zero;
reads operator + (reads a,reads b)
{
	return (reads){MD1(a.hsh1+b.hsh1),MD2(a.hsh2+b.hsh2)};
}
reads operator - (reads a,reads b)
{
	return (reads){MD3(a.hsh1-b.hsh1),MD4(a.hsh2-b.hsh2)};
}
reads operator * (reads a,reads b)
{
	return (reads){1ll*a.hsh1*b.hsh1%mod1,1ll*a.hsh2*b.hsh2%mod2};
}
struct node
{
	reads num;
	int data,nxt;
};
node edge[M+1];
string s;
int len,head[K+1],dp[N+1];
void adder(reads x,int d)
{
	int ds=(x.hsh1^x.hsh2)&K;
	for (int i=head[ds];i>0;i=edge[i].nxt)
		if (edge[i].num==x)
		{
			edge[i].data+=d;
			return;
		}
	edge[++len]=(node){x,d,head[ds]},head[ds]=len;
	return;
}
int query(reads x)
{
	int ds=(x.hsh1^x.hsh2)&K;
	for (int i=head[ds];i>0;i=edge[i].nxt)
		if (edge[i].num==x)
			return edge[i].data;
	return 0;
}
int main()
{
	bool op=1;
	reads res;
	for (int i=0;i<26;++i) rd[i]=(reads){(int)(RAND()%mod1),(int)(RAND()%mod2)};
	cin>>s;
	if (s.length()<=5000) len=s.length();
	else len=25;
	for (int i=0;i<s.length();++i) op&=(s[i]==s[0]);
	if (op)
	{
		printf("%d\n",(s.length()+1)>>1);
		return 0;
	}
	for (int i=s.length();i>=1;--i)
	{
		res=zero;
		for (int j=1;j<=len&&i+j-1<=s.length();++j) res=res*(reads){Base1,Base2}+rd[s[i+j-2]-'a'],adder(res,1),dp[i]=max(dp[i],query(res)-dp[i+j]);
	}
	printf("%d\n",dp[1]);
	return 0;
}