#include <bits/stdc++.h>
using namespace std;
int n, dp[1000005][3]; string A, B;
int main(){
cin >> n >> A >> B;
//this allows the indexes to aline.
A = " " + A; B = " " + B;
vector<vector<int> > dp(n+5, vector<int>(3, 1e9));
dp[0][0] = 0;
for (int i = 1; i <= n; i++) {
for (int j = 0; j < 3; j++){
bool eq = (j == 0 && A[i] == B[i]) || (j - 1 == B[i] - '0');
dp[i][j] = min(dp[i][j], dp[i - 1][0] + (A[i - 1] == B[i - 1]) * !eq + (j == 1 || j == 2));
dp[i][j] = min(dp[i][j], dp[i - 1][1] + (B[i - 1] == '0') * !eq + (j == 2));
dp[i][j] = min(dp[i][j], dp[i - 1][2] + (B[i - 1] == '1') * !eq + (j == 1));
}
}
cout<<min({dp[n][0], dp[n][1], dp[n][2]})<<endl;
}
