#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;
int dp[1000001][3][2];
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//random_start();
int n;
string a,b;
cin >> n >> a >> b;
rep(i,n+1) rep(j,3) rep(k,2) dp[i][j][k] = INF;
dp[0][2][0] = 0;
rep(i,n)
{
rep(xd,4) rep(st,3)
{
rep(xr,2)
{
dp[i][st][xr^1] = min(dp[i][st][xr^1],dp[i][st][xr]+1-xr);
if(st == 0 || st == 1) dp[i][2][xr] = min(dp[i][2][xr],dp[i][st][xr]);
else rep(d,2) dp[i][d][xr] = min(dp[i][d][xr],dp[i][st][xr]+1);
}
}
rep(st,3)
{
rep(xr,2)
{
int val = (a[i]-'0');
if(st != 2) val = st;
if(xr == 1) val ^= 1;
if(val != (b[i]-'0')) dp[i][st][xr] = INF;
dp[i+1][st][xr] = dp[i][st][xr];
}
}
}
int ans = INF;
rep(i,3) rep(j,2) ans = min(ans,dp[n][i][j]);
cout << ans << "\n";
}
