#include <bits/stdc++.h>
using namespace std;
const int INF = 1e7;
int N;
string A, B;
void Read() {
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
cin >> N >> A >> B;
}
int Solve() {
vector<array<array<int, 4>, 4>> dp(N + 1); // dp[pos][second_last_operation][last_operation]
// dp[pos] means A[pos...N] = B[pos...N]
// operation 0 = skip operation
// operation 1 = off operation
// operation 2 = on operation
// operation 3 = xor operation
for (int i = 0; i <= N; i++) {
for (int j = 0; j < 4; j++) {
for (int k = 0; k < 4; k++) {
dp[i][j][k] = INF;
}
}
}
dp[0][0][0] = 0;
for (int pos = 0; pos < N; pos++) {
// continue extending basic operations
for (int second_last = 0; second_last < 4; second_last++) {
for (int last = 0; last < 4; last++) {
if (A[pos] == B[pos]) { // operation skip (0)
dp[pos + 1][last][0] = min(dp[pos + 1][last][0], dp[pos][second_last][last]);
}
if (B[pos] == '0') { // operation off (1)
dp[pos + 1][last][1] = min(dp[pos + 1][last][1], (last != 1) + dp[pos][second_last][last]);
}
if (B[pos] == '1') { // operation on (2)
dp[pos + 1][last][2] = min(dp[pos + 1][last][2], (last != 2) + dp[pos][second_last][last]);
}
if (A[pos] != B[pos]) { // operation xor (3)
dp[pos + 1][last][3] = min(dp[pos + 1][last][3], (last != 3) + dp[pos][second_last][last]);
}
}
}
// mergable operations
dp[pos + 1][0][1] = min(dp[pos + 1][0][1], dp[pos][1][2]); // off on off (from off off/on off)
dp[pos + 1][0][2] = min(dp[pos + 1][0][2], dp[pos][2][1]); // on off on (from on on/off on)
dp[pos + 1][0][3] = min(dp[pos + 1][0][3], dp[pos][1][2]); // off on xor (from off on/xor xor)
dp[pos + 1][0][3] = min(dp[pos + 1][0][3], dp[pos][2][1]); // on off xor (from on off/xor xor)
dp[pos + 1][0][2] = min(dp[pos + 1][0][2], dp[pos][3][1]); // xor off on (from xor xor/on on)
dp[pos + 1][0][1] = min(dp[pos + 1][0][1], dp[pos][3][2]); // xor on off (from xor xor/off off)
}
int res = INF;
for (int second_last = 0; second_last < 4; second_last++) {
for (int last = 0; last < 4; last++) {
res = min(res, dp[N][second_last][last]);
}
}
return res;
}
int main() {
Read();
cout << Solve() << "\n";
return 0;
}
