#include "bits/stdc++.h"
//#pragma GCC optimize("O3")
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll>pairll;
typedef long double ld;
#define fr first
#define sc second
#define pb push_back
#define INF 100000000000000007
#define I 100000000000007
#define N 100007
#define endl '\n'
#define MOD 998244353
ll n,d[N*10][7];
string a,b;
int main()
{
cin>>n;
cin>>a>>b;
a=" "+a;
b=" "+b;
d[0][1]=1;
d[0][2]=1;
d[0][3]=2;
d[0][4]=2;
d[0][5]=1;
for(int i=1;i<=n;i++){
if(a[i]==b[i]){
d[i][5]=INF;
d[i][0]=min(d[i-1][0],min(d[i-1][1],min(d[i-1][2],min(d[i-1][3],min(d[i-1][4],d[i-1][5])))));
if(a[i]=='0'){
d[i][1]=min(d[i-1][0]+1,min(d[i-1][1],min(d[i-1][2]+1,min(d[i-1][3],min(d[i-1][4]+1,d[i-1][5]+1)))));
d[i][2]=INF;
d[i][3]=INF;
d[i][4]=min(d[i-1][0]+2,min(d[i-1][1]+2,min(d[i-1][2]+1,min(d[i-1][3]+1,min(d[i-1][4],d[i-1][5]+1)))));
}else{
d[i][1]=INF;
d[i][2]=min(d[i-1][0]+1,min(d[i-1][1]+1,min(d[i-1][2],min(d[i-1][3]+1,min(d[i-1][4],d[i-1][5]+1)))));
d[i][3]=min(d[i-1][0]+2,min(d[i-1][1]+1,min(d[i-1][2]+2,min(d[i-1][3],min(d[i-1][4]+1,d[i-1][5]+1)))));
d[i][4]=INF;
}
}else{
d[i][5]=min(d[i-1][0]+1,min(d[i-1][1]+1,min(d[i-1][2]+1,min(d[i-1][3],min(d[i-1][4],d[i-1][5])))));
d[i][0]=INF;
if(a[i]=='0'){
d[i][1]=INF;
d[i][2]=min(d[i-1][0]+1,min(d[i-1][1]+1,min(d[i-1][2],min(d[i-1][3]+1,min(d[i-1][4],d[i-1][5]+1)))));
d[i][3]=min(d[i-1][0]+2,min(d[i-1][1]+1,min(d[i-1][2]+2,min(d[i-1][3],min(d[i-1][4]+1,d[i-1][5]+1)))));
d[i][4]=INF;
}else{
d[i][1]=min(d[i-1][0]+1,min(d[i-1][1],min(d[i-1][2]+1,min(d[i-1][3],min(d[i-1][4]+1,d[i-1][5]+1)))));
d[i][2]=INF;
d[i][3]=INF;
d[i][4]=min(d[i-1][0]+2,min(d[i-1][1]+2,min(d[i-1][2]+1,min(d[i-1][3]+1,min(d[i-1][4],d[i-1][5]+1)))));
}
}
//cout<<i<<" "<<d[i][0]<<" "<<d[i][1]<<" "<<d[i][2]<<" "<<d[i][3]<<" "<<d[i][4]<<" "<<d[i][5]<<endl;
}
cout<<min(d[n][0],min(d[n][1],min(d[n][2],min(d[n][3],min(d[n][4],d[n][5])))))<<endl;
return 0;
}
