#include<bits/stdc++.h>
using namespace std;


#define endl "\n"
#define LL long long
#define FOR(i,n) for(int i=0;i<n;i++)
#define deb(x) cerr<<#x<<" : "<<x<<" "
#define dnl cerr<<endl


const LL base[2] = {37,59};
const LL mod[2] = {(LL)1e9+7,(LL)1e9+9};
const int maxn = 4e6+40;
LL P[2][maxn];
LL H[2][maxn];
LL R[2][maxn];
LL inv[2][maxn];

inline LL power(LL a,LL b,const int m){
    if(b==0)return 1;
    if(b==1)return a%m;
    LL x = power(a,b/2,m);
    x = (x*x)%m;
    if(b%2 != 0){
        x = (x*a)%m;
    }
    return x;
}

inline LL range_hash(int idx,int l,int r){
    LL h = H[idx][r]-H[idx][l-1]+mod[idx];
    h %= mod[idx];
    if(l>0)h *= inv[idx][l-1];
    h %= mod[idx];
//    cerr<<"Shoja :";
//    deb(idx);deb(l);deb(r);deb(h);dnl;
    return h;
}
int n;
inline LL reverse_hash(int idx,int l,int r){
    LL h = R[idx][l] - R[idx][r+1] + mod[idx];
    h %= mod[idx];
    int bad = n-r;
    if(bad>0){
        h *= inv[idx][bad];
        h %= mod[idx];
    }
//    cerr<<"Ulta :";
//    deb(idx);deb(l);deb(r);deb(h);dnl;
    return h;
}

inline LL drevhash(int l,int r){
    LL x = reverse_hash(0,l,r);
    LL y = reverse_hash(1,l,r);
    return (x<<31)^y;
}

inline LL dhash(int l,int r){
    LL x = range_hash(0,l,r);
    LL y = range_hash(1,l,r);
    return (x<<31)^y;
}

int finpref(int l,int n){
    int lo=1,hi=(n-l)+1;
    hi /= 2;
    int ans = 0;

    for(int mid=lo;mid<=hi;mid++){
        if( dhash(l,l+mid-1)==drevhash(l+mid,l+mid+mid-1) ){
            ans = mid;
            return ans;
        }
    }

//    while(lo<=hi){
//        int mid = (lo+hi)>>1;
//        deb(l);deb(n);deb(mid);dnl;
//        if( dhash(l,l+mid-1)==drevhash(l+mid,l+mid+mid-1) ){
//            ans = mid;
//            lo = mid+1;
//        }
//        else hi = mid-1;
//    }
    return ans;
}

int finsuff(int l,int n){
    int lo=1,hi=(n-l)+1;
    hi /= 2;
    int ans = 0;

    for(int mid=lo;mid<=hi;mid++){
        if( dhash(n-mid+1,n)==drevhash(n-mid-mid+1,n-mid) ){
            ans = mid;
            return ans;
        }
    }
//    while(lo<=hi){
//        int mid = (lo+hi)>>1;
////        deb(mid);dnl;
//        if( dhash(n-mid+1,n)==drevhash(n-mid-mid+1,n-mid) ){
//            ans = mid;
//            lo = mid+1;
//        }
//        else hi = mid-1;
//    }
    return ans;
}



//#define cnd tree[idx]
//#define lnd idx*2,b,(b+e)/2
//#define rnd idx*2+1,(b+2)/2 + 1,e
//#define lc tree[idx*2]
//#define lr tree[idx*2+1]
//typedef pair<int,int> pii;
//struct segtree{
//    pii tree[4*maxn] ;
//    void build(int idx,int b,int e,int val){
//        cnd=pii(val,-1);
//        if(b!=e){
//            build(lnd);
//            build(rnd);
//        }
//    }
//    void update(int idx,int b,int e)
//};



void solve(int cs){
    string s;
    cin>>s;
    n = (int)s.size();
    FOR(i,2){
        P[i][0] = 1;
        for(int j=1;j<=n+5;j++)P[i][j] = (P[i][j-1]*base[i])%mod[i];
    }
    FOR(i,2){
        inv[i][n+4] = power(P[i][n+4],mod[i]-2,mod[i]);
        for(int j=n+3;j>=0;j--){
            inv[i][j] = (inv[i][j+1]*base[i])%mod[i];
        }
    }

    FOR(j,2){
        for(int i=1;i<=n;i++){
            H[j][i] = (H[j][i-1] + P[j][i]*s[i-1])%mod[j];
        }
        for(int i=n,c=1;i>0;i--,c++){
            R[j][i] = ( R[j][i+1] + P[j][c]*s[i-1] )%mod[j];
        }
    }

    int l=1,r=n;
    int ans = n;
    while( l<r ){
        int x = finpref(l,r);
//        deb(l);deb(r);deb(x);
        if(x < 1)break;
        l += x;
    }
//    deb(l);deb(r);dnl;
    while( l<r ){
        int x = finsuff(l,r);
//        deb(l);deb(r);deb(x);dnl;
        if(x < 1)break;
        r -= x;
    }

    cout<<r-l+1<<endl;
}

/*
ATTAATTA

*/
int main(){

    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);

    int t=1;
//    cin>>t;
    for(int cs=1;cs<=t;cs++)solve(cs);
}