#include<bits/stdc++.h>
using namespace std;
#define all(fl) fl.begin(),fl.end()
#define pb push_back
#define fi first
#define se second
#define for1(i,j,k) for(int i=j;i<=k;i++)
#define for2(i,j,k) for(int i=j;i>=k;i--)
#define for3(i,j,k,l) for(int i=j;i<=k;i+=l)
#define lb lower_bound
#define ub upper_bound
#define sz(a) (int)a.size()
#define pii pair<int,int>
#define pli pair<long long,int>
#define gcd __gcd
#define lcm(x,y) x*y/__gcd(x,y)
#define pil pair<int,long long>
const int maxn=1e6+9;
int f[maxn][10];
int a[maxn],b[maxn];
vector<int> state[10]={{0},{1},{2},{3},{1,2},{1,3},{2,1},{2,3},{3,1},{3,2}};
int nxt[2][10];
int cost[10][10];
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("temp.INP","r",stdin);
//freopen("temp.OUT","w",stdout);
int n;
cin>>n;
string s,t;
cin>>s>>t;
s=" "+s;
t=" "+t;
for1(i,1,n){
if (s[i]=='1')a[i]=1;
if (t[i]=='1')b[i]=1;
}
for1(i,0,1){
for1(j,0,9){
int ni=i;
for(auto v:state[j]){
if (v==0)continue;
if (v==1)ni=1;
if (v==2)ni=0;
if (v==3)ni=1-ni;
}
nxt[i][j]=ni;
}
}
for1(i,0,9){
for1(j,0,9){
if (i==0)cost[i][j]=sz(state[j]);
if (j==0)cost[i][j]=0;
if (i!=0&&j!=0&&i!=j){
if (sz(state[i])==1&&sz(state[j])==1){
cost[i][j]=1;
}
if (sz(state[i])==1&&sz(state[j])==2){
bool fl=1;
for (auto v:state[j]){
if (v==state[i][0]){
fl=0;
break;
}
}
cost[i][j]=fl+1;
}
if (sz(state[i])==2&&sz(state[j])==1){
bool fl=1;
for (auto v:state[i]){
if (v==state[j][0]){
fl=0;
break;
}
}
cost[i][j]=fl;
}
if (sz(state[i])==2&&sz(state[j])==2){
cost[i][j]=1;
}
}
}
}
for1(i,0,n){
for1(j,0,9){
f[i][j]=n+1;
}
}
f[0][0]=0;
for1(i,1,n){
for1(j,0,9){
if (nxt[a[i]][j]==b[i]){
for1(k,0,9){
f[i][j]=min(f[i][j],f[i-1][k]+cost[k][j]);
}
}
}
}
int ans=n+1;
for1(i,0,9)ans=min(ans,f[n][i]);
cout<<ans;
//for1(i,0,9)for1(j,0,9)cout<<i<<" "<<j<<" "<<cost[i][j]<<'\n';
}
