палиндром

#include <bits/stdc++.h>
using namespace std;
#define ld long double
#define ll long long
const int MAXN  = 239300;
ll INF  = 9223372036854775000;
ll MD  = 1000000009;
ll L  = 53;
ll MAXSIZE = 2000005;
vector<ll>st(MAXSIZE,0);
vector<ll> createHash(string s)
{
    vector<ll>h(s.size()+1,0);
    for(int i=0; i<s.size(); ++i)
    {
        h[i+1] = (h[i]*L +s[i])%MD;
    }
    return h;
}
ll getHash(vector<ll>&h,ll l,ll r)
{
    return (h[r] - h[l-1]*st[r-l+1] +MD*MD)%MD;
}

int main()
{
   ifstream file("data.txt");
    ll N,M,S1,S2,LS;
    file>>N;
    string s1,s2;
    file>>s2;
    s1 = s2;
    reverse(s2.begin(),s2.end());
    st[0] = 1;
    for(int i=1; i<MAXSIZE; ++i)
    {
        st[i] = (st[i-1]*L)%MD;
    }
//cout<<s1<<" "<<s2<<endl;
    vector<ll>h1 = createHash(s1);
    vector<ll>h2 = createHash(s2);
    int c = 0;
    int maxP = 1;
    for(int i=1; i<=s1.size(); ++i)
    {


        int l,r,m;
        l = i ;
        r = s1.size()+1;
        while(l+1<r){

           m = (l+r)/2;
 cout<<i<<" "<<m<<" "<<s1.size() - m+1<<" "<< s1.size() - i+1<<" "<<(getHash(h1,i,m) == getHash(h2,s1.size() - m+1, s1.size() - i+1))<<endl;
           if(getHash(h1,i,m) == getHash(h2,s1.size() - m+1, s1.size() - i+1)){
                l = m ;
           }else{
                r = m;
           }

        };
cout<<-i+l+1<<endl;
        maxP = max(maxP,-i+l+1);


    }
    cout<<maxP;



}