// author : anhtun_hi , nqg
#include <bits/stdc++.h>
#define ll long long
#define ii pair<ll, ll>
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define reset(h, v) memset(h, v, sizeof h)
#define Forv(i, a) for(auto& i : a)
#define For(i, a, b) for(int i = a; i <= b; ++i)
#define Ford(i, a, b) for(int i = a; i >= b; --i)
#define c_bit(i) __builtin_popcountll(i)
#define Bit(mask, i) ((mask >> i) & 1LL)
#define onbit(mask, i) ((mask) bitor (1LL << i))
#define offbit(mask, i) ((mask) &~ (1LL << i))
using namespace std;
namespace std {
template <typename T, int D>
struct _vector : public vector <_vector <T, D - 1>> {
static_assert(D >= 1, "Dimension must be positive!");
template <typename... Args>
_vector(int n = 0, Args... args) : vector <_vector <T, D - 1>> (n, _vector <T, D - 1> (args...)) {}
};
template <typename T> struct _vector <T, 1> : public vector <T> {
_vector(int n = 0, const T& val = T()) : vector <T> (n, val) {}
};
template <class A, class B> bool minimize(A &a, B b){return a > b ? a = b, true : false;}
template <class A, class B> bool maximize(A &a, B b){return a < b ? a = b, true : false;}
}
const int dx[] = {0, 0, +1, -1}, dy[] = {-1, +1, 0, 0}, LOG = 20, base = 311, inf = 1e9 + 5;
const int MAXN = 1e6 + 5;
const ll mod = 1e9 + 7;
const ll oo = 1e18;
//#define int long long
int n; ll dp[MAXN][2][2][2];
string a, b;
ll solve(int i, bool j, bool h, bool k)
{
if(i > n) return 0;
if (~dp[i][j][h][k]) return dp[i][j][h][k];
ll res = oo;
int cur = a[i] - '0';
if(j) cur = 0;
if(h) cur = 1;
if(k) cur ^= 1;
if(cur == b[i] - '0'){
For(_j, 0, 1) For(_h, 0, 1) if(!(_j == _h &&_j == 1)) For(_k, 0, 1){
minimize(res, solve(i + 1, _j, _h, _k) + (_j && _j != j) + (_h && _h != h) + (_k && _k != k));
}
}
return dp[i][j][h][k] = res;
}
void Solve() {
cin >> n >> a >> b;
a = '0' + a, b = '0' + b;
reset(dp, -1);
cout << solve(0, 0, 0, 0) << '\n';
}
int32_t main() {
cin.tie(0) -> sync_with_stdio(0);
if(fopen("JOI19_lamps.inp", "r")) {
freopen("JOI19_lamps.inp", "r", stdin);
freopen("JOI19_lamps.out", "w", stdout);
}
int t = 1;
// cin >> t;
for (int test = 1; test <= t; test++) {
Solve();
}
return 0;
}
