#include <bits/stdc++.h>
using namespace std;
#define MIN(a, b) a = min(a, b)
int n, dp[1000005][3]; string A, B;
int main()
{
cin >> n >> A >> B;
A = " " + A; B = " " + B;
memset(dp, 0x3f, sizeof(dp));
dp[0][0] = 0;
for (int i = 1; i <= n; i++)
for (int j : {0, 1, 2})
{
bool eq = (!j and A[i] == B[i]) or (j - 1 == B[i] - '0');
int &DP = dp[i][j];
MIN(DP, dp[i - 1][0] + min(1,(A[i - 1] == B[i - 1]) * !eq + (j == 1 or j == 2)));
MIN(DP, dp[i - 1][1] + (i == 1 or B[i - 1] == '0') * !eq + (j == 2));
MIN(DP, dp[i - 1][2] + (i == 1 or B[i - 1] == '1') * !eq + (j == 1));
}
cout<<min({dp[n][0], dp[n][1], dp[n][2]})<<endl;
}
