#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
ll n;
string s;
//vector<int>v[26];
ll mod=1000000829;
ll a[400005];
ll w[400005];
ll val=0;
ll mult=101;
ll fastpow(ll z, ll u)
{
    if (u==0) return 1;
    if (u%2)
    {
        return (z*fastpow(z, u-1))%mod;
    }
    ll se=fastpow(z, u/2);
    se*=se;
    return se%mod;
}
ll getval(ll b, ll e)
{
//cerr<<b<<" "<<e<<": ";
    if (b==0) return a[e];
    ll z=a[e]-((a[b-1]*fastpow(mult, e-b+1))%mod);
    while (z<0) z+=mod;
    z%=mod;
//cerr<<z<<endl;
    return z;
}
ll getvalb(ll b, ll e)
{
    if (e==n-1) return w[b];
    ll z=w[b]-((w[e-1]*fastpow(mult, e-b+1))%mod);
    while (z<0) z+=mod;
    z%=mod;
    return z;
}
bool ok(int z)
{
    int m=z+n;
    if (m%2)
    {
        ll d=n-m/2-1;
        if (m/2+1>=n) return true;
        ll x=getvalb(m/2+1, n-1);
        ll y=getval(m/2-d,m/2-1);
        if (x%mod==y%mod) return true;
        return false;
    }
    else{
        ll d=n-m/2;
        if (m/2>=n) return true;
        ll x=getvalb(m/2, n-1);
        ll y=getval(m/2-d,m/2-1);
        if (x%mod==y%mod) return true;
        return false;
    }
    return false;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin>>n;
    cin>>s;
    for (int i=0; i<n; ++i)
    {
        //v[s[i]-'a'].push_back(i);
        val*=mult;
        val%=mod;
        val+=s[i]-'a'+1;
        val%=mod;
        a[i]=val;
    }
    val=0;
    for (int i=n-1; i>=0; --i)
    {
        //v[s[i]-'a'].push_back(i);
        val*=mult;
        val%=mod;
        val+=s[i]-'a'+1;
        val%=mod;
        w[i]=val;
    }
    for (int i=0; i<n; ++i)
    {
        if (ok(i))
        {
            cout<<i;
            return 0;
        }
    }
    cout<<n;
}