Manacher

　　

#include <bits/stdc++.h>
using namespace std;
const int maxn = 3e5;
char s[maxn], str[maxn];
int len1, len2, p[maxn], ans;

void init(){
    str[0] = '$';
    str[1] = '#';
    for(int i=0; i<len1; i++){
        str[i*2+2] = s[i];
        str[i*2+3] = '#';
    }
    len2 = len1 << 1 + 2;
    str[len2] = '*';
}
void manacher(){
    int id=0, mx=0;
    for(int i=1; i<len2; i++){
        if(mx>i)p[i]=min(p[id<<1-i], mx-i);
        else p[i]=1;
        for(;str[i+p[i]] == str[i-p[i]];p[i]++);
        if(p[i]+i > mx){
            mx=p[i]+i;
            id = i;
        }
    }
}
int main(){
    //freopen("in", "r", stdin);
    while(scanf("%s", s), strcmp(s,"end")){
        len1 = strlen(s);
        init();
        manacher();
        for(int i=0; i<len2; i++)
            ans = max(ans, p[i]);
        printf("%d\n", ans);
    }
}