#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
#define pb push_back
#define f first
#define s second
const int MAXN = 1e6 + 10;
const int INF = 1e8;
int N;
string As, Bs;
int a[MAXN], b[MAXN];
int dp[MAXN][3][2];
int main() {
cin >> N;
cin >> As >> Bs;
As = ' ' + As;
Bs = ' ' + Bs;
for (int i = 1; i <= N; i++) {
a[i] = As[i] - '0';
b[i] = Bs[i] - '0';
}
a[0] = b[0] = 0; // initialize to be the same so no toggle needed
for (int i = 0; i < MAXN; i++) {
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 2; k++) {
dp[i][j][k] = INF;
}
}
}
dp[0][0][0] = 0;
for (int i = 0; i < N; i++) {
// case 1: nothing
int tog = a[i] ^b[i];
int cCost = dp[i][0][0];
if (cCost != INF) {
// case 1a: continue nothing
int nTog = a[i + 1] ^b[i + 1];
int nCost = cCost + (tog < nTog);
dp[i + 1][0][0] = min(dp[i + 1][0][0], nCost);
// case 1b: add a set
for (int nSet = 0; nSet < 2; nSet++) {
int nTog = nSet ^b[i + 1];
int nCost = cCost + 1 + (tog < nTog);
dp[i + 1][1][nSet] = min(dp[i + 1][1][nSet], nCost);
}
}
// case 2: 1 set
for (int cSet = 0; cSet < 2; cSet++) {
int tog = cSet ^b[i];
int cCost = dp[i][1][cSet];
if (cCost != INF) {
// case 2a: continue/change cSet
for (int nSet = 0; nSet < 2; nSet++) {
int nTog = nSet ^b[i + 1];
int nCost = cCost + (cSet ^ nSet) + (tog < nTog);
dp[i + 1][1][nSet] = min(dp[i + 1][1][nSet], nCost);
}
// case 2b: stop set
int nTog = a[i + 1] ^b[i + 1];
int nCost = cCost + (tog < nTog);
dp[i + 1][0][0] = min(dp[i + 1][0][0], nCost);
// case 2c: add second set that is opposite of cSet
nTog = (cSet ^ 1) ^ b[i + 1];
nCost = cCost + 1 + (tog < nTog);
dp[i + 1][2][cSet] = min(dp[i + 1][2][cSet], nCost);
}
}
// case 3: 2 sets, cSet is the the base set
for (int cSet = 0; cSet < 2; cSet++) {
int tog = cSet ^1 ^b[i];
int cCost = dp[i][2][cSet];
if (cCost != INF) {
// case 2a: continue cSet
int nTog = cSet ^1 ^b[i + 1];
int nCost = cCost + (tog < nTog);
dp[i + 1][2][cSet] = min(dp[i + 1][2][cSet], nCost);
// case 2b: stop second set
nTog = cSet ^ b[i + 1];
nCost = cCost + (tog < nTog);
dp[i + 1][1][cSet] = min(dp[i + 1][1][cSet], nCost);
}
}
}
int ans = INF;
assert(dp[N][0][1] == INF);
// case 1: no set
ans = min(ans, dp[N][0][0]);
// case 2: 1 set
ans = min(ans, dp[N][1][0]);
ans = min(ans, dp[N][1][1]);
// case 2: 2 set
ans = min(ans, dp[N][2][0]);
ans = min(ans, dp[N][2][1]);
// cout << dp[7][0][0] << endl;
// cout << dp[8][0][0] << endl;
assert(ans >= 0);
cout << ans << endl;
}
