#include<bits/stdc++.h>
#define file(F) freopen(#F".in","r",stdin),freopen(#F".out","w",stdout)
using namespace std;
using ll=long long;
using ull=unsigned long long;
void Solve();
static constexpr unsigned P = 131;
const int N = 2e5+25;
int n;
char s0[N],s1[N];
int p[N];
ull h[N],g[N];
ull pw[N];
int ans;
void Find(char *s,char *t) {
   for(int i=1;i<=n;i++) h[i]=h[i-1]*P+s[i];
   for(int i=n;i>=1;i--) g[i]=g[i+1]*P+t[i];
   for(int i=1,m=0,r=0;i<=n;i++) {
      p[i]=0;
      if(i<=r) p[i]=min(r-i+1,p[m+m-i]);
      while(s[i-p[i]]==s[i+p[i]]) ++p[i];
      if(i+p[i]>r) m=i,r=i+p[i]-1;
   }
   for(int i=1;i<=n;i++) {
      int j=max(ans+1,p[i]); for(;j<i;j++)
         if(h[i-p[i]]-h[i-j-1]*pw[j-p[i]+1]!=
            g[i+p[i]-2]-g[i+j-1]*pw[j-p[i]+1])
               break; ans=max(ans,j-1);
   }
}
signed main() {
   cin.tie(nullptr)->sync_with_stdio(false);
   Solve();
}
void Solve() {
   cin>>n;
   for(int i=1;i<=n;i++) cin>>s0[i<<1],s0[i<<1|1]='#';
   for(int i=1;i<=n;i++) cin>>s1[i<<1],s1[i<<1|1]='#';
   n+=n+1; s0[1]=s1[1]='#'; s0[0]=s1[0]='@';
   pw[0]=1; for(int i=1;i<=n;i++) pw[i]=pw[i-1]*P;
   Find(s0,s1);
   reverse(s0+1,s0+n+1);
   reverse(s1+1,s1+n+1);
   Find(s1,s0);
   printf("%d\n",ans);
}