#include <bits/stdc++.h>
using namespace std;
#define sz(v) int(v.size())
#define ar array
typedef long long ll;
const int N = 6e1+10, MOD = 1e9+7;
const ll INF = 1e18+10;
// 0 = empty
// 1 = {0}
// 2 = {1}
// 3 = {0, 1}
// 4 = {1, 0}
pair<int, int> trans(int prv, int nxt, int state) {
if (prv == nxt) {
if (nxt == 0) {
if (state == 0) return {0, state};
else if (state == 1) return {0, state};
else if (state == 2) return {0, 0};
else if (state == 3) return {0, 1};
else if (state == 4) return {0, state};
} else {
if (state == 0) return {0, state};
else if (state == 1) return {0, 0};
else if (state == 2) return {0, state};
else if (state == 3) return {0, state};
else if (state == 4) return {0, 2};
}
}
if (nxt == 1) {
if (state == 0) return {1, 2};
else if (state == 1) return {1, 3};
else if (state == 2) return {0, state};
else if (state == 3) return {0, state};
else if (state == 4) return {0, 2};
} else {
if (state == 0) return {1, 1};
else if (state == 1) return {0, state};
else if (state == 2) return {1, 4};
else if (state == 3) return {0, 1};
else if (state == 4) return {0, state};
}
assert(false);
}
int prv[5][2], cur[5][2];
void solve() {
int n; cin >> n;
string s, t; cin >> s >> t;
for (int i = 0; i < 5; i++) {
for (int j = 0; j < 2; j++) {
prv[i][j] = cur[i][j] = MOD;
}
}
prv[0][0] = 0;
for (int i = 0; i < n; i++) {
int x = s[i] - '0', y = t[i] - '0';
for (int prv_state = 0; prv_state < 5; prv_state++) {
for (int prv_flip = 0; prv_flip < 2; prv_flip++) {
for (int me = 0; me < 2; me++) {
int flip = me ^ y;
auto [cost, nxt_state] = trans(x, me, prv_state);
cost += flip && !prv_flip;
cur[nxt_state][flip] = min(cur[nxt_state][flip], prv[prv_state][prv_flip] + cost);
}
}
}
for (int j = 0; j < 5; j++) {
for (int k = 0; k < 2; k++) {
prv[j][k] = cur[j][k], cur[j][k] = MOD;
}
}
}
int ans = MOD;
for (int i = 0; i < 5; i++)
for (int j = 0; j < 2; j++)
ans = min(ans, prv[i][j]);
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(false); cin.tie(0);
int T = 1;
// cin >> T;
while (T--) solve();
}
