#include <bits/stdc++.h>
//#define int long long
//#pragma GCC optimize("Ofast")
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4")
#define file(s) freopen(s".in","r",stdin); freopen(s".out","w",stdout);
#define forev(i, b, a) for(int i = (b); i >= (a); --i)
#define forn(i, a, b) for(int i = (a); i <= (b); ++i)
#define all(x) x.begin(), x.end()
#define sz(s) (int)s.size()
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define s second
#define f first
using namespace std;
typedef pair < long long, long long > pll;
typedef pair < int, int > pii;
typedef unsigned long long ull;
typedef vector < pii > vpii;
typedef vector < int > vi;
typedef long double ldb;
typedef long long ll;
typedef double db;
const int inf = 1e9, maxn = 4e5 + 148, mod = 1e9 + 7, N = 1e6 + 11;
const int dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1}, block = 333;
const pii base = mp(1171, 3307), Mod = mp(1e9 + 7, 1e9 + 9);
const db eps = 1e-12, pi = 3.14159265359;
const ll INF = 1e18;
int n, dp[N][3];
char s[N], t[N];
char f (char c, int j) {
if (!j)
return c;
return '0' + j - 1;
}
int get (int i, int j, int k) {
int res = 0;
if (j != k && j)//we need to open new interval
++res;
if ((i == 1 || f(s[i - 1], k) == t[i - 1]) && f(s[i], j) != t[i])
++res;
//if s[i - 1] = t[i - 1] and s[i] = t[i] then don't need to add anything
//if s[i - 1] != t[i - 1] and s[i] = t[i] then we already added 1 before
//if s[i - 1] != t[i - 1] and s[i] != t[i] then we just add i to the last interval of operation XOR
//otherwise we need to add new operation XOR
return res;
}
main () {
scanf("%d\n%s\n%s", &n, s + 1, t + 1);
dp[0][1] = dp[0][2] = inf;
for (int i = 1; i <= n; ++i) {
for (int j = 0; j < 3; ++j)
dp[i][j] = inf;
for (int j = 0; j < 3; ++j)
for (int k = 0; k < 3; ++k)
dp[i][j] = min(dp[i][j], dp[i - 1][k] + get(i, j, k));
}
cout << min({dp[n][0], dp[n][1], dp[n][2]});
}
