#include<bits/stdc++.h>
#define inf 0x7fffffff
#define RG register int
using namespace std;
typedef long long ll;
const ll mod = 998244353;
const long double eps = 1e-11;
//using namespace std;
inline ll read(){
	ll x=0,f=1;char ch=getchar();
	while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
	return x*f;
}
int n,w,h;
char ch[4000005],pat[4000005 * 2];
int pos,r[4000005 * 2],ans;
int main(){
	int i,j,u,v;
	scanf("%s",ch+1);
	n=strlen(ch+1);
	pat[0]='@';
	for(i=1;i<=n;i++) pat[2*i-1]=ch[i],pat[2*i]='@';
	pos=0,r[0]=0;
	for(i=1;i<=2*n;i++){
		if(i<=pos+r[pos]) r[i]=min(pos+r[pos]-i,r[pos*2-i]);
		while(i>r[i]&&pat[i+r[i]+1]==pat[i-r[i]-1]) r[i]++;
		if(i+r[i]>pos+r[pos]) pos=i;
	}
	int l, rr, L = 1, R = 2 * n - 1;
	for(l = 2; l < R; l += 2) if(l - r[l] < L) L = l + 1;
	for(rr = R - 1; rr > L; rr -= 2) if(rr + r[rr] > R) R = rr - 1;
	printf("%d\n", (R - L + 2) / 2);
    return 0;
}