#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
using ll = long long;
using pll = pair<ll, ll>;
void solve() {
ll n; cin >> n;
string a, b; cin >> a >> b;
vector<vector<ll>> dp(n, vector<ll>(3, 1e18));
dp[0][0] = ((a[0] == b[0]) ? 0 : 1);
dp[0][1] = ((0 == b[0]) ? 1 : 2);
dp[0][2] = ((1 == b[0]) ? 1 : 2);
for (ll i = 1; i < n; i++) {
for (ll prev = 0; prev < 3; prev++) {
char xprev = ((prev == 0) ? a[i-1] : ((prev == 1) ? '0' : '1'));
bool dprev = (xprev != b[i-1]);
for (ll cur = 0; cur < 3; cur++) {
char x = ((cur == 0) ? a[i] : ((cur == 1) ? '0' : '1'));
ll cost;
if (cur == 0) cost = 0;
else if (cur == 1) cost = (prev == 1 ? 0 : 1);
else cost = (prev == 2 ? 0 : 1);
bool d = (x != b[i]);
dp[i][cur] = min(dp[i][cur], dp[i-1][prev]+cost+((d && !dprev) ? 1 : 0));
}
}
}
cout << min(dp[n-1][0], min(dp[n-1][1], dp[n-1][2])) << endl;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//___________________________
solve();
return 0;
}
