#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
//#define int long long
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define ppb pop_back
#define eb emplace_back
#define g0(a) get<0>(a)
#define g1(a) get<1>(a)
#define g2(a) get<2>(a)
#define g3(a) get<3>(a)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using db = double;
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using iii = tuple<int, int, int>;
using iiii = tuple<int, int, int, int>;
template<class key, class value = null_type, class cmp = less<key> >
using ordered_set = tree<key, value, cmp, rb_tree_tag, tree_order_statistics_node_update>;
int N, mem[1000005][3][2];
bool A[1000005], B[1000005];
char C;
int dp(int n, int a, bool b) {
if (n == N + 1) return (a == 2 ? 0 : 1e9);
if (mem[n][a][b] != -1) return mem[n][a][b];
int ret = 1e9;
bool x = A[n];
if (a != 2) x = a;
for (int k = 0; k < 3; k++)
ret = min(ret, dp(n + 1, k, x != B[n]) + ((k != a) && k != 2));
mem[n][a][b] = ret + ((x != B[n]) && !b);
return mem[n][a][b];
}
main() {
memset(mem, -1, sizeof mem);
ios::sync_with_stdio(0);
cin.tie(0);
cin >> N;
for (int i = 1; i <= N; i++) {
cin >> C;
A[i] = C == '1';
}
for (int i = 1; i <= N; i++) {
cin >> C;
B[i] = C == '1';
}
cout << min({dp(1, 0, 0) + 1, dp(1, 1, 0) + 1, dp(1, 2, 0)}) << '\n';
}
