#include <bits/stdc++.h>
#define int long long
using namespace std;
int a;
string s,s1;
int f[1000001][4];
int bruh=1e18;
char exc(char c,int x){
if (x==1){
return '1';
}else if (x==2){
return '0';
}else{
return c;
}
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> a;
cin >> s >> s1;
s='#'+s;
s1='#'+s1;
for (int i=0;i<=a;i++){
for (int j=1;j<=3;j++){
f[i][j]=bruh;
}
}
f[0][3]=0;
for (int i=0;i<a;i++){
for (int j=1;j<=3;j++){
for (int k=1;k<=3;k++){
int cost= f[i][j];
if ((j!=k || j==3) && k!=3){
cost++;
}
if (exc(s[i+1],k)!=s1[i+1] && (i==0 || exc(s[i],j)==s1[i])){
//cout << "ok" << "\n";
cost++;
}
f[i+1][k]=min(f[i+1][k],cost);
}
}
}
int min1=min({f[a][1],f[a][2],f[a][3]});
cout << min1 << "\n";
return 0;
}
