//Author: Kevin
#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
#define ll long long
#define ull unsigned ll
#define pb emplace_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
#define inf 0x3f3f3f3f
#define pii pair<int,int>
#define lb(v,x) (int)(lower_bound(ALL(v),x)-v.begin())
#define ub(v,x) (int)(upper_bound(ALL(v),x)-v.begin())
#define uni(v) v.resize(unique(ALL(v))-v.begin())
#define longer __int128_t
void die(string S){puts(S.c_str());exit(0);}
int d1[4004000],d2[4004000];
bool ok1[4004000],ok2[4004000];
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	string s;
	cin>>s;
	int n=sz(s);
	int l=0,r=-1;
	for(int i=0;i<n;i++)
	{
		if(i<=r)
			d1[i]=min(r-i,d1[l+r-i]);
		while(i+d1[i]+1<n&&i-d1[i]-1>=0&&s[i+d1[i]+1]==s[i-d1[i]-1])
			d1[i]++;
		if(i+d1[i]>r)
		{
			l=i-d1[i];
			r=i+d1[i];
		}
	}
	l=0,r=-1;
	for(int i=0;i<n-1;i++)
	{
		if(i+1<=r)
			d2[i]=min(r-i,d2[l+r-i-1]);
		while(i+d2[i]+1<n&&i-d2[i]>=0&&s[i+d2[i]+1]==s[i-d2[i]])
			d2[i]++;
		if(i+d2[i]>r)
		{
			l=i-d2[i]+1;
			r=i+d2[i];
		}
	}
	ok1[0]=1;
	int lst=0;
	for(int i=1;i<=n;i++)
	{
		// if(i<n&&lst>=i-d1[i])
		// 	ok1[i]=1;
		if(lst>=i-d2[i-1])
			ok1[i]=1;
		if(ok1[i])
			lst=i;
		// if(ok1[i])
		// 	cerr<<i<<endl;
	}
	ok2[n]=1;
	lst=n;
	for(int i=n-1;i>=0;i--)
	{
		// if(i&&i+d1[i-1]>=lst)
		// 	ok2[i]=1;
		if(i+d2[i-1]>=lst)
			ok2[i]=1;
		if(ok2[i])
			lst=i;
		// if(ok2[i])
		// 	cerr<<i<<endl;
	}
	lst=0;
	int ans=n;
	for(int i=1;i<=n;i++)
	{
		if(ok1[i-1])
			lst=i-1;
		if(ok2[i])
			ans=min(ans,i-lst);
	}
	cout<<ans<<'\n';
	return 0;
}