#include <bits/stdc++.h> 

using i64 = long long; 
using u64 = unsigned long long; 
using u32 = unsigned; 

using u128 = unsigned __int128; 
using i128 = __int128; 

void solve() {
	int n;
	std::string S, T;
	std::cin >> n >> S >> T;
	int ans = 0;
	for(int i = 0; i < n; i ++) if(S[i] != T[i]) ans++;
	std::cout << ans;
} 

int main() { 
	std::ios::sync_with_stdio(false); 
	std::cin.tie(nullptr); 

	int T = 1; 
	//std::cin >> T; 

	while (T--) { 
		solve(); 
	} 
	return 0; 
}