#include #define rep(i,n) for(int i = 0; i < (n); ++i) #define srep(i,s,t) for (int i = s; i < t; ++i) #define drep(i,n) for(int i = (n)-1; i >= 0; --i) using namespace std; typedef long long int ll; typedef pair P; #define yn {puts("Yes");}else{puts("No");} #define MAX_N 200005 int main() { int n; cin >> n; string s, t; cin >> s >> t; int ans = 0; rep(i,n)if(s[i] != t[i])ans++; cout << ans << endl; return 0; }