#include <cstdio>

#include <cstring>

#define N 22200000

#define min(x, y) ((x) < (y) ? (x) : (y))

#define max(x, y) ((x) > (y) ? (x) : (y))

int p[N];

char s[N];

int pos = 1, maxright, ans, n;

int main()

{

	int i, j;

	scanf("%s", s + 1);

	n = strlen(s + 1);

	s[0] = '$', s[n * 2 + 1] = '#';

	for(i = n; i >= 1; i--) s[i * 2] = s[i], s[i * 2 - 1] = '#';

	n = n * 2;

	for(i = 1; i <= n; i++)

	{

		p[i] = 1;

		if(i <= maxright)

			p[i] = min(p[pos * 2 - i], maxright - i + 1);

		while(s[i - p[i]] == s[i + p[i]]) p[i]++;

		if(maxright < i + p[i] - 1)

		{

			pos = i;

			maxright = i + p[i] - 1;

		}

		ans = max(ans, p[i] - 1);

	}

	printf("%d\n", ans);

	return 0;

}