// yukicoder: No.491 10^9+1と回文
// 2019.6.27 bal4u

#include <stdio.h>
#include <string.h>

typedef long long ll;

#if 1
#define gc() getchar_unlocked()
#define pc(c) putchar_unlocked(c)
#else
#define gc() getchar()
#define pc(c) putchar(c)
#endif

ll in(char *s) {
	ll n = 0;
	while (*s) n = 10*n + (*s++ & 0xf);
	return n;
}

int ins(char *s) {
	char *p = s;
	do *s = gc();
	while (*s++ > ' ');
	*--s = 0;
	return s - p;
}

void out(int n) {
	int i;
	char ob[20];

	if (!n) pc('0');
	else {
		i = 0; while (n) ob[i++] = n%10 + '0', n/=10;
		while (i--) pc(ob[i]);
	}
	pc('\n');
}

//                              10 11  12  13   14   15    16    17     18
int a[20] = {0,0,0,0,0,0,0,0,0,0,9, 9, 90, 90, 900, 900, 9000, 9000, 90000, 90000};
int s[20] = {0,0,0,0,0,0,0,0,0,0,9,18,108,198,1098,1998,10998,19998,109998,199998};
char S[20], t[20]; int w;
int p10[10] = {1, 10, 100, 1000, 10000, 100000, 1000000, 10000000 };
ll N;

int cnt(char *t, int k) {
	int i, r = t[k] - '0' + (k > 0);
	i = k - 1;
	while (i >= 0) r += (t[i] - '0' - (i == 0)) * p10[k - i], i--;
	return r;
}

int main()
{
	int i, j, k, f;
	ll n;
	
	w = ins(S);
	if (w < 10) { out(0); return 0; }
	N = in(S);
	j = k = (w-9) >> 1, f = (w-9) & 1;
	memcpy(t, S, k); if (f) t[j++] = S[k];
	for (i = k-1; i >= 0; i--) t[j++] = t[i];
	while (j < w) t[j++] = '0'; t[j] = 0;
	memcpy(t+9, t, w-9);
	n = in(t);
	if (!f) k--;
	if (n > N) {
		i = k;
		while (1) {
			if (t[i] > '0') { t[i]--; break; }
			else t[i--] = '9';
		}
	}
	out(s[w-1] + cnt(t, k));
	return 0;
}