#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#include<bits/stdc++.h>
using namespace std;
#define mp make_pair
#define INF 10000000
#define MOD 1000000007
#define MID (l+r)/2
#define HASHMOD 2305843009213693951
#define ll long long
#define ull unsigned long long
#define F first
#define S second
typedef pair<ll, ll> ii;
typedef pair<ii, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef map<int, int> mii;
#define EPS 1e-6
string a,b;
// operations:
// 0 none
// 1 toggle
// 2 set 0
// 3 toggle + set 0
// 4 set 1
// 5 toggle + set 1
#define Q(w, cost) dp[n][x] = min(dp[n][x], rec(n-1, w)+cost);
int dp[1004000][6];
int rec(int n, int x){
if(n<0) return 0;
if(dp[n][x]!=-MOD) return dp[n][x];
dp[n][x] = MOD;
if(b[n]=='1'){
if(x==2 || x==3){ Q(2,0);}
else{ Q(2,1);}
if(x==5){ Q(5,0);}
else if(x==1 || x==4){ Q(5,1);}
else{ Q(5,2);}
}
else if(b[n]=='0'){
if(x==4 || x==5){ Q(4,0);}
else{ Q(4,1);}
if(x==3){ Q(3,0);}
else if(x==1 || x==2){ Q(3,1);}
else{ Q(3,2);}
}
if(a[n]==b[n]){ Q(0, 0);}
else{
if(x%2==1){ Q(1, 0);}
else{ Q(1, 1);}
}
return dp[n][x];
}
int main(){
int n;
cin>>n;
cin>>a>>b;
for(int i=0;i<n;i++){
for(int j=0;j<6;j++) dp[i][j] = -MOD;
}
cout<<rec(n-1, 0);
}
