#include <bits/stdc++.h>
#define IO_OP std::ios::sync_with_stdio(0); std::cin.tie(0);
#define F first
#define S second
#define V vector
#define PB push_back
#define MP make_pair
#define EB emplace_back
#define ALL(v) (v).begin(), (v).end()
using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef V<int> vi;
string _reset = "\u001b[0m", _yellow = "\u001b[33m", _bold = "\u001b[1m";
void DBG() { cerr << "]" << _reset << endl; }
template<class H, class...T> void DBG(H h, T ...t) {
cerr << to_string(h);
if(sizeof ...(t)) cerr << ", ";
DBG(t...);
}
#ifdef CHEISSMART
#define debug(...) cerr << _yellow << _bold << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define debug(...)
#endif
const int INF = 1e9 + 7;
signed main()
{
IO_OP;
int n;
string s, t;
cin >> n >> s >> t;
s = '0' + s, t = '0' + t;
vi dp{0, INF, INF};
// nothing, change to 0, change to 1
for(int i = 1; i <= n; i++) {
vi ndp{INF, INF, INF};
for(int j = 0; j < 3; j++) {
int ps = j == 0 ? s[i - 1] - '0' : j - 1, pt = t[i - 1] - '0';
for(int k = 0; k < 3; k++) {
int ns = k == 0 ? s[i] - '0' : k - 1, nt = t[i] - '0';
int cost = 0;
if(k && k != j) cost++;
if((ps ^ pt) == 0 && (ns ^ nt) == 1)
cost++;
ndp[k] = min(ndp[k], dp[j] + cost);
}
}
swap(dp, ndp);
}
cout << *min_element(ALL(dp)) << '\n';
}
