#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
using ll = long long;
using ld = long double;
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
// http://xorshift.di.unimi.it/splitmix64.c
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
gp_hash_table<ll, ll, custom_hash> app;
//const int MOD = 998244353;
//const int MOD = 1e9 + 7;
constexpr ll INF = 1e9;
vector<ll> a;
ll n, m, k, q, x, y, z, w, h, T;
string s, t;
double p;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
T = 1;
//cin >> T;
while (T--) {
cin >> n;
cin >> s >> t;
int a[n], b[n];
for (int i = 0; i < n; i++) {
a[i] = s[i] - '0';
b[i] = t[i] - '0';
}
int dp[n + 1][3][2] = {}; // dp[index][setNumber (2 if don't change)][toggle]. Notice that toggle always comes after number
for (int i = 0; i <= n; i++) {
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 2; k++) {
dp[i][j][k] = INF;
}
}
}
int changetoggle[2][2] = {};
changetoggle[0][1] = 1;
int changenumber[3][3] = {};
changenumber[0][1] = 1; changenumber[1][0] = 1; changenumber[2][0] = 1; changenumber[2][1] = 1;
dp[0][2][0] = 0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 2; k++) {
for (int jj = 0; jj < 3; jj++) {
for (int kk = 0; kk < 2; kk++) {
int num = a[i];
if (jj != 2) num = jj;
if (kk) num = 1 - num;
if (num != b[i]) continue;
dp[i + 1][jj][kk] = min(dp[i + 1][jj][kk], dp[i][j][k] + changenumber[j][jj] + changetoggle[k][kk]);
}
}
}
}
}
int ans = INF;
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 2; k++) {
ans = min(ans, dp[n][j][k]);
}
}
printf("%i\n", ans);
}
}
