#include <bits/stdc++.h>
using namespace std;
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii ;
typedef pair<ll, ll> pll ;
typedef vector<pii> vii ;
typedef vector<int> veci ;
typedef vector<pll> vll ;
typedef vector<ll> vecll;
// find_by_order order_of_key
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define F first
#define S second
#define pb push_back
#define endl '\n'
#define Mp make_pair
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " = " << x << endl
#define set_dec(x) cout << fixed << setprecision(x);
#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io freopen("in.txt" , "r" , stdin) ; freopen("out.txt" , "w" , stdout);
#define lb lower_bound
#define ub upper_bound
#define for1(n) for(int i=1;i<=n;i++)
#define for0(n) for(int i=0;i<n;i++)
#define forn(n) for(int i=n;i>0;i--)
#define pq priority_queue <pii, vector<pii>, greater<pii>>
const ll mod = 1e9+7 ;// 998244353 ;// 1e9+9;
ll inf=1e18;
const int N=1e6+100,L=21,bs=701,NN=1e6;
int A[N],B[N],C[N],D[N],E[N],n,m,k,q,dp[N][2],dpp[N][2][2],pre[N],dist[N],vis[N];
vector<int>g[N];
string s,t;
int main(){
fast_io
cin>>n>>s>>t;
s='0'+s;
t='0'+t;
for1(n)s[i]-='0';
for1(n)t[i]-='0';
dp[0][0]=0;
dp[0][1]=mod;
dpp[0][0][0]=mod;
dpp[0][0][1]=mod;
dpp[0][1][0]=mod;
dpp[0][1][1]=mod;
for1(n){
dp[i][0]=min(min(dp[i-1][0],dp[i-1][1]),min(dpp[i-1][0][1],dpp[i-1][1][1]));
dp[i][1]=min(min(dp[i-1][0]+1,dp[i-1][1]),min(dpp[i-1][0][1]+1,dpp[i-1][1][1]));
dp[i][(s[i]==t[i])]=mod;
if(t[i]==t[i-1]){
dpp[i][0][0]=min(dpp[i-1][0][0],dpp[i-1][1][1]);
dpp[i][0][1]=min(min(dp[i-1][0],dp[i-1][1])+1,min(dpp[i-1][0][1],dpp[i-1][1][0]+1));
dpp[i][1][0]=min(dpp[i-1][1][0],dpp[i-1][0][1]+1);
dpp[i][1][1]=min(min(dp[i-1][0]+1,dp[i-1][1])+1,min(dpp[i-1][1][1],dpp[i-1][0][0]+2));
}
else{
dpp[i][0][0]=min(dpp[i-1][1][0],dpp[i-1][0][1]);
dpp[i][0][1]=min(min(dp[i-1][0],dp[i-1][1])+1,min(dpp[i-1][1][1],dpp[i-1][0][0]+1));
dpp[i][1][0]=min(dpp[i-1][0][0]+1,dpp[i-1][1][1]);
dpp[i][1][1]=min(min(dp[i-1][0]+1,dp[i-1][1])+1,min(dpp[i-1][0][1]+1,dpp[i-1][1][0]+1));
}
dpp[i][0][1]=min(dpp[i][0][1],dpp[i][0][0]+1);
dpp[i][1][1]=min(dpp[i][1][1],dpp[i][1][0]+1);
}
cout<<min(min(dp[n][0],dp[n][1]),min(dpp[n][0][1],dpp[n][1][1]))<<endl;
}
