#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(x) (x).begin(), (x).end()
void ckmin(int &x, int y) {
x = min(x, y);
}
int main() {
cin.tie(0)->sync_with_stdio(false);
int n;
string a, b;
cin >> n >> a >> b;
vector<vector<int>> dp(2, vector<int> (3, 1e9));
dp[0][0] = 0;
for (int i = 0; i < n; i++) {
for (int x : {0, 1})
for (int y : {0, 1, 2})
ckmin(dp[x][0], dp[x][y]);
for (int y : {0, 1, 2})
ckmin(dp[0][y], dp[1][y]);
for (int x : {0, 1})
for (int y : {1, 2})
ckmin(dp[x][y], dp[x][0] + 1);
for (int y : {0, 1, 2})
ckmin(dp[1][y], dp[0][y] + 1);
for (int x : {0, 1}) {
for (int y : {0, 1, 2}) {
char have = (y == 0 ? a[i] : (y - 1 + '0'));
if ((have == b[i]) == x)
dp[x][y] = 1e9;
}
}
}
int ans = 1e9;
for (int x : {0, 1})
for (int y : {0, 1, 2})
ans = min(ans, dp[x][y]);
cout << ans << '\n';
return 0;
}
