#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;
}