#include <bits/stdc++.h>
#define int long long
using namespace std;
const int maxn = 1e6 + 6;
/// 0: on
/// 1: off
/// 2: tog
/// 3: on & tog
/// 4: off & tog
/// 5: tog & on
/// 6: tog & off
/// 7: do nothing
int dp[maxn][8];
void Minimize(int &a, const int &b)
{
a = min(a, b);
}
void Update(int i, int j)
{
if(j == 0) /// on
{
dp[i][j] = min(dp[i][j], dp[i - 1][0]);
dp[i][j] = min(dp[i][j], dp[i - 1][1] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][2] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][3]);
dp[i][j] = min(dp[i][j], dp[i - 1][4] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][5]);
dp[i][j] = min(dp[i][j], dp[i - 1][6] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][7] + 1);
}
else if(j == 1) /// off
{
dp[i][j] = min(dp[i][j], dp[i - 1][0] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][1]);
dp[i][j] = min(dp[i][j], dp[i - 1][2] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][3] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][4]);
dp[i][j] = min(dp[i][j], dp[i - 1][5] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][6]);
dp[i][j] = min(dp[i][j], dp[i - 1][7] + 1);
}
else if(j == 2) /// tog
{
dp[i][j] = min(dp[i][j], dp[i - 1][0] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][1] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][2]);
dp[i][j] = min(dp[i][j], dp[i - 1][3]);
dp[i][j] = min(dp[i][j], dp[i - 1][4]);
dp[i][j] = min(dp[i][j], dp[i - 1][5]);
dp[i][j] = min(dp[i][j], dp[i - 1][6]);
dp[i][j] = min(dp[i][j], dp[i - 1][7] + 1);
}
else if(j == 3) /// on & tog
{
dp[i][j] = min(dp[i][j], dp[i - 1][0] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][1] + 2);
dp[i][j] = min(dp[i][j], dp[i - 1][2] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][3]);
dp[i][j] = min(dp[i][j], dp[i - 1][4] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][5] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][6] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][7] + 2);
}
else if(j == 4) /// off & tog
{
dp[i][j] = min(dp[i][j], dp[i - 1][0] + 2);
dp[i][j] = min(dp[i][j], dp[i - 1][1] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][2] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][3] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][4]);
dp[i][j] = min(dp[i][j], dp[i - 1][5] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][6] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][7] + 2);
}
else if(j == 5) /// tog & on
{
dp[i][j] = min(dp[i][j], dp[i - 1][0] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][1] + 2);
dp[i][j] = min(dp[i][j], dp[i - 1][2] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][3] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][4] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][5]);
dp[i][j] = min(dp[i][j], dp[i - 1][6] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][7] + 2);
}
else if(j == 6) /// tog & off
{
dp[i][j] = min(dp[i][j], dp[i - 1][0] + 2);
dp[i][j] = min(dp[i][j], dp[i - 1][1] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][2] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][3] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][4] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][5] + 1);
dp[i][j] = min(dp[i][j], dp[i - 1][6]);
dp[i][j] = min(dp[i][j], dp[i - 1][7] + 2);
}
else if(j == 7)
{
dp[i][j] = min(dp[i][j], dp[i - 1][0]);
dp[i][j] = min(dp[i][j], dp[i - 1][1]);
dp[i][j] = min(dp[i][j], dp[i - 1][2]);
dp[i][j] = min(dp[i][j], dp[i - 1][3]);
dp[i][j] = min(dp[i][j], dp[i - 1][4]);
dp[i][j] = min(dp[i][j], dp[i - 1][5]);
dp[i][j] = min(dp[i][j], dp[i - 1][6]);
dp[i][j] = min(dp[i][j], dp[i - 1][7]);
}
}
int32_t main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
if(fopen("test.inp", "r")) freopen("test.inp", "r", stdin), freopen("test.out", "w", stdout);
string s, t;
int n;
cin >> n;
cin >> s >> t;
fill_n(&dp[0][0], maxn*8, 1e9);
if(s[0] == '0' && t[0] == '1')
{
dp[0][0] = dp[0][2] = 1;
dp[0][4] = dp[0][5] = 2;
}
if(s[0] == '0' && t[0] == '0')
{
dp[0][1] = 1;
dp[0][3] = dp[0][6] = 2;
dp[0][7] = 0;
}
if(s[0] == '1' && t[0] == '0')
{
dp[0][1] = dp[0][2] = 1;
dp[0][3] = dp[0][6] = 2;
}
if(s[0] == '1' && t[0] == '1')
{
dp[0][0] = 1;
dp[0][4] = dp[0][5] = 2;
dp[0][7] = 0;
}
for(int i = 1; i < s.length(); i++)
{
if(s[i] == '0' && t[i] == '1')
{
Update(i, 0);
Update(i, 2);
Update(i, 4);
Update(i, 5);
}
if(s[i] == '0' && t[i] == '0')
{
Update(i, 1);
Update(i, 3);
Update(i, 6);
Update(i, 7);
}
if(s[i] == '1' && t[i] == '1')
{
Update(i, 0);
Update(i, 4);
Update(i, 5);
Update(i, 7);
}
if(s[i] == '1' && t[i] == '0')
{
Update(i, 1);
Update(i, 2);
Update(i, 3);
Update(i, 6);
}
}
int ans = 1e9;
for(int i = 0; i <= 7; i++)
{
ans = min(ans, dp[s.length() - 1][i]);
}
cout << ans;
}
