#include <bits/stdc++.h>
#define rep(i,l,r) for (int i = l; i < r; i++)
#define pb push_back
#define debug(x) cerr << #x << " : " << x << endl;
using namespace std;
constexpr int N = 1e6+10;
int dp[N],l[N][3];
int main(){
ios_base :: sync_with_stdio(0); cin.tie(0);
int n;
cin >> n;
string s,t;
cin >> s >> t;
s = '#'+s;
t = '#'+t;
rep(i,1,n+1){
if (s[i] != t[i]) l[i][2] = 1+l[i-1][2];
else l[i][2] = 0;
if (t[i] == '1') l[i][1] = l[i-1][1]+1;
else l[i][0] = l[i-1][0]+1;
if (s[i] == t[i]){
dp[i] = dp[i-1];
continue;
}
dp[i] = dp[i-max({l[i][1],l[i][0],l[i][2]})]+1;
}
cout << dp[n];
}
