#include<bits/stdc++.h>

using namespace std;


int main(void)
{
	string s;
	cin >> s;
	vector<int> vi(256, -1);
	int maxx = 0, start = -1;
	for (int i = 0; i < s.size(); i++)
	{
		if (vi[s[i]] > start)start = vi[s[i]];
		vi[s[i]] = i;
		maxx = max(maxx, i - start);
	}
	cout << maxx;
}