#include <bits/stdc++.h>
using namespace std;
#define int long long
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
const int N = 1e5 + 5, INF = 1e14;
vector<vector<int> > dp(N, vector<int> (3, INF));
// 0 - OFF
// 1 - ON
// 2 - UNUSED
char getvalue(char a, int x)
{
if(x == 0) return '0';
if(x == 1) return '1';
return a;
}
void Solve()
{
int n;
cin >> n;
string a, b;
cin >> a >> b;
dp[0][2] = 0;
for(int i = 1; i <= n; i++)
{
// cout << "i = " << i << endl;
char cur_a = a[i - 1], cur_b = b[i - 1];
for(int j = 0; j < 3; j++)
{
for(int k = 0; k < 3; k++)
{
int value = dp[i - 1][k];
// if the last value had an operation and the current value has a diff / no operation
if(j != k && j != 2)
{
value++;
}
// if the answer after the operation is not consistent with b[i]
if((i == 1 || getvalue(a[i - 2], k) == b[i - 2]) && getvalue(cur_a, j) != cur_b)
{
value++;
}
dp[i][j] = min(dp[i][j], value);
}
}
}
// for(int i = 0; i <= n; i++)
// {
// for(int j = 0; j < 3; j++)
// {
// cout << dp[i][j] << " ";
// }
// cout << "\n";
// }
int ans = INF;
for(int i = 0; i < 3; i++)
{
ans = min(ans, dp[n][i]);
}
cout << ans << "\n";
}
int32_t main()
{
auto begin = std::chrono::high_resolution_clock::now();
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
for(int i = 1; i <= t; i++)
{
//cout << "Case #" << i << ": ";
Solve();
}
auto end = std::chrono::high_resolution_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
return 0;
}
