//Source.cpp
//いつもの
#ifdef LOCAL
#define _USE_MATH_DEFINES
#include<iostream>
#include<string>
#include<vector>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<unordered_set>
#include<unordered_map>
#include<list>
#include<array>
#include<algorithm>
#include<numeric>
#include<cmath>
#include<climits>
#include<iomanip>
#include<cctype>
#include<sstream>
#include<regex>
#include<bitset>
#include<random>
#include<complex>
#include<cassert>
#else
#include<bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#ifdef ONLINE_JUDGE
#include<atcoder/all>
using namespace atcoder;
/*#else
#define gcd __gcd
#define lcm __detail::__lcm*/
#endif
#endif
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#ifdef LOCAL
//*
#include<atcoder/all>
using namespace atcoder;
//*/
unsigned popcount(unsigned x){
	return __popcnt(x);
}
unsigned popcountll(ull x){
	return __popcnt64(x);
}
unsigned parity(unsigned x){
	return popcount(x)%2;
}
unsigned parityll(ull x){
	return popcountll(x)%2;
}
unsigned clz(unsigned x){
	if(x==0)
		throw;
	unsigned cnt=__lzcnt(x);
	return cnt;
}
unsigned clzll(ull x){
	if(x==0)
		throw;
	unsigned cnt=__lzcnt64(x);
	return cnt;
}
unsigned ctz(unsigned x){
	if(x==0)
		throw;
	x&=~x+1;
	unsigned cnt=0;
	if(x&0xffff0000)
		cnt|=16;
	if(x&0xff00ff00)
		cnt|=8;
	if(x&0xf0f0f0f0)
		cnt|=4;
	if(x&0xcccccccc)
		cnt|=2;
	if(x&0xaaaaaaaa)
		cnt|=1;
	return cnt;
}
unsigned ctzll(ull x){
	if(x==0)
		throw;
	x&=~x+1;
	unsigned cnt=0;
	if(x&0xffffffff00000000)
		cnt|=32;
	if(x&0xffff0000ffff0000)
		cnt|=16;
	if(x&0xff00ff00ff00ff00)
		cnt|=8;
	if(x&0xf0f0f0f0f0f0f0f0)
		cnt|=4;
	if(x&0xcccccccccccccccc)
		cnt|=2;
	if(x&0xaaaaaaaaaaaaaaaa)
		cnt|=1;
	return cnt;
}
unsigned ffs(unsigned x){
	if(x==0)
		return 0;
	return ctz(x)+1;
}
unsigned ffsll(ull x){
	if(x==0)
		return 0;
	return ctzll(x)+1;
}
#define __builtin_popcount popcount
#define __builtin_popcountll popcountll
#define __builtin_parity parity
#define __builtin_parityll parityll
#define __builtin_clz clz
#define __builtin_clzll clzll
#define __builtin_ctz ctz
#define __builtin_ctzll ctzll
#define __builtin_ffs ffs
#define __builtin_ffsll ffsll
#endif
constexpr int mod=1e9+7;
constexpr int Mod=998244353;
constexpr int inf=mod;
constexpr ll linf=(ll)mod*mod;
struct fastio{
	fastio(){
		cin.tie(0);
		ios::sync_with_stdio(0);
		cout<<fixed<<setprecision(20);
	};
}fio;
template<class T>
bool chmax(T&a,const T&b){
	if(a<b){
		a=b;
		return 1;
	}
	return 0;
}
template<class T>
bool chmin(T&a,const T&b){
	if(a>b){
		a=b;
		return 1;
	}
	return 0;
}
int main(){
	int n;
	string s,t;
	cin>>n>>s>>t;
	int ans=0;
	for(int i=0;i<n;i++)
		ans+=s[i]!=t[i];
	cout<<ans<<endl;
}