#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include<bits/stdc++.h>
using namespace std;
#define FTB(i,a,b) for(LL i=a;i<=b;i++)
#define FT(i,a,b) for(LL i=a;i<b;i++)
#define FGB(i,a,b) for(LL i=a;i>=b;i--)
#define FG(i,a,b) for(LL i=a;i>b;i--)
#define endl "\n"
#define PB push_back
#define mp make_pair
#define fi first
#define se second
#define PI 3.1415926535897
#define lbnd(dau,cuoi,giatri) lower_bound(dau,cuoi,giatri)
#define ubnd(dau,cuoi,giatri) upper_bound(dau,cuoi,giatri)
typedef double DB;
typedef long long LL;
typedef unsigned long long UL;
typedef long double LD;
typedef pair<LL,LL> II;
typedef vector<LL> VI;
typedef vector<bool> VB;
LL n,res=0,tmp;
string a,b;
string s;
int main(){
ios::sync_with_stdio(false);cin.tie(0);
cin>>n;
cin>>a;
cin>>b;
a="1"+a;
b="1"+b;
FTB(i,1,n/2){
s="";
s+=a[i];
s+=b[i];
s+=a[n+1-i];
s+=b[n+1-i];
sort(s.begin(),s.end());
tmp=1;
FT(i,1,4){
if(s[i]!=s[i-1]) tmp++;
}
if(tmp==4){
res+=2;
}
else if(tmp==2){
if(s[1]==s[2]){
res++;
}
}
else if(tmp==3){
if(a[i]==a[n-i+1]) res+=2;
else if(b[i]==b[n-i+1]) res+=2;
else res++;
}
}
if(n%2==1){
n++;
if(a[n/2]!=b[n/2]) res++;
}
cout<<res;
return 0;
}
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