#include <bits/stdc++.h>
#define fi first
#define se second
#define eb emplace_back
#define em emplace
#define all(v) v.begin(), v.end()
using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
const int MAX = 1010101;
const int INF = 1e9;
const ll LINF = 1e18;
int dp[3][MAX];
int main() {
ios::sync_with_stdio(false); cin.tie(0);
int n;
string s, t;
cin >> n >> s >> t;
dp[0][0] = 1 + (t[0] == '1');
dp[1][0] = 1 + (t[0] == '0');
dp[2][0] = 0 + (s[0] != t[0]);
for(int i = 1; i < n; i++) {
bool b = (t[i] == '1');
dp[0][i] = min(dp[0][i-1] + (b && t[i-1] == '0'),
dp[2][i-1] + 1 + (b && s[i-1] == t[i-1]));
dp[1][i] = min(dp[1][i-1] + (!b && t[i-1] == '1'),
dp[2][i-1] + 1 + (!b && s[i-1] == t[i-1]));
dp[2][i] = min({
dp[0][i-1] + (s[i] != t[i] && t[i-1] == '0'),
dp[1][i-1] + (s[i] != t[i] && t[i-1] == '1'),
dp[2][i-1] + (s[i] != t[i] && t[i-1] == s[i-1])
});
}
cout << min({dp[0][n-1], dp[1][n-1], dp[2][n-1]});
}
