#include <bits/stdc++.h>
using namespace std;
int dp[1000001], sumA[4], sumB[4], mx[4];
bool prv[4];
int main() {
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int n; cin >> n;
string A, B; cin >> A >> B;
prv[1] = prv[3] = true;
memset(dp, 0x3f3f3f3f, sizeof(dp));
dp[0] = 0;
for (int i = 1; i <= n; i++) {
int& ret = dp[i];
if (!prv[0] && B[i-1] == '1') sumA[0]++;
if (prv[0] && B[i-1] == '0') sumB[0]++;
ret = min(ret, mx[0]+sumA[0] + 1);
prv[0] = B[i-1] == '1';
if (prv[1] && B[i-1] == '0') sumA[1]++;
if (!prv[1] && B[i-1] == '1') sumB[1]++;
ret = min(ret, mx[1] + sumA[1] + 1);
prv[1] = B[i-1] == '1';
if (!prv[2] && A[i-1] == B[i-1]) sumA[2]++;
if (prv[2] && A[i-1] != B[i-1]) sumB[2]++;
ret = min(ret, mx[2] + sumA[2] + 1);
prv[2] = A[i-1] == B[i-1];
if (prv[3] && A[i-1] != B[i-1]) sumA[3]++;
if (!prv[3] && A[i-1] == B[i-1]) sumB[3]++;
ret = min(ret, mx[3] + sumA[3]);
prv[3] = A[i-1] == B[i-1];
for (int j = 0; j < 4; j++) mx[j] = min(mx[j], dp[i-1] - sumB[j]);
}
cout << dp[n];
return 0;
}
