#include <bits/stdc++.h>
using namespace std;
#define ar array
#define sz(v) int(std::size(v))
using i64 = long long;
const int INF = 1e9;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N;
cin >> N;
string A, B;
cin >> A >> B;
int dp[3][2], ndp[3][2];
for (int x : {0,1,2}) for (int y : {0,1}) dp[x][y] = INF;
dp[0][0] = 0;
for (int i = 0; i < N; i++) {
for (int x : {0,1,2}) for (int y : {0,1}) ndp[x][y] = INF;
for (int x1 : {0,1,2}) for (int y1 : {0,1}) for (int x2 : {0,1,2}) for (int y2 : {0,1})
ndp[x2][y2] = min(ndp[x2][y2], dp[x1][y1] + (x1 != x2 && x2 > 0) + (y2 > y1));
for (int x : {0,1,2}) for (int y : {0,1}) {
int v = (x ? x - 1 : A[i] - '0') ^ y;
if (v != B[i] - '0') ndp[x][y] = INF;
}
swap(dp, ndp);
}
int ans = INF;
for (int x : {0,1,2}) for (int y : {0,1}) ans = min(ans, dp[x][y]);
cout << ans << '\n';
}
