#include<bits/stdc++.h>
using namespace std;
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define dbg(x) cout << #x << '=' << x << '\n';
#define ll long long
#define sz size()
#define x first
#define y second
#define pi pair <int, int>
#define pii pair <int, pi>
#define vi vector <int>
const ll mod = 1e9 + 7;
int n, dp[4][2];
bool a[1000002], b[1000002];
int32_t main(){
ios_base :: sync_with_stdio(0); cin.tie(); cout.tie();
cin>>n;
for(int i=1; i<=n; i++){
char c;
cin>>c;
if(c=='1') a[i]=1;
}
for(int i=1; i<=n; i++){
char c;
cin>>c;
if(c=='1') b[i]=1;
}
///cout<<a[1];
dp[0][0]=0;
dp[1][0]=dp[2][0]=dp[3][0]=1;
for(int i=1; i<=n; i++){
dp[0][1]=dp[1][1]=dp[2][1]=dp[3][1]=1e9;
if(a[i]==b[i]) dp[0][1]=min(dp[0][0], min(dp[1][0], min(dp[2][0], dp[3][0])));
else dp[3][1]=min(dp[0][0]+1, min(dp[1][0]+1, min(dp[2][0]+1, dp[3][0])));
if(b[i]==1) dp[1][1]=min(dp[0][0]+1, min(dp[1][0], min(dp[2][0]+1, dp[3][0]+1)));
else dp[2][1]=min(dp[0][0]+1, min(dp[1][0]+1, min(dp[2][0], dp[3][0]+1)));
for(int j=0; j<=3; j++) dp[j][0]=dp[j][1];
//cout<<i<<" "<<dp[1][0]<<" "<<dp[2][0]<<" "<<dp[3][0]<<" "<<dp[4][0]<<endl;
}
cout<<min(dp[0][0], min(dp[1][0], min(dp[2][0], dp[3][0])));
}
