#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 7;
int main() {
int N;
cin >> N;
string A, B;
cin >> A >> B;
vector<array<array<int, 2>, 3>> dp(N + 1);
for (int i = 0; i < 3; i++)
for (int j = 0; j < 2; j++)
if (i != 0 || j != 0)
dp[0][i][j] = INF;
for(int i = 1 ; i <= N; ++i) {
int x = A[i - 1] - '0';
int y = B[i - 1] - '0';
for(int j = 0; j < 3; j++) {
for(int k = 0; k < 2; k++) {
int &F = dp[i][j][k];
F = INF;
if (j == 0 && k != (x ^ y))
continue;
if (j == 1 && k != y)
continue;
if (j == 2 && k == y)
continue;
for (int t = 0; t < 3; t++) {
F = min(F, dp[i - 1][t][0] + int(t != j && j > 0) + k);
F = min(F, dp[i - 1][t][1] + int(t != j && j > 0));
}
}
}
}
int ans = INF;
for(int i = 0; i < 3 ; i++)
for(int j = 0; j < 2; j++)
ans = min(ans, dp[N][i][j]);
cout << ans << '\n';
}
