#include <bits/stdc++.h>
using namespace std;
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#define flash ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
#define debug(x) cerr << " - " << #x << ": " << x << endl;
#define debugs(x, y) cerr << " - " << #x << ": " << x << " " << #y << ": " << y << endl;
#define all(x) (x).begin(),(x).end()
#define sz(x) (ll)x.size()
#define ll long long
#define INF 1000000000
#define MOD 1000000007
#define pb push_back
#define ve vector<ll>
#define dos pair<ll,ll>
#define vedos vector<dos>
#define rand mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
struct greateri
{
template<class T>
bool operator()(T const &a, T const &b) const { return a > b; }
};
string kal,kal1;
ll n;
ll dp[1000001][8];
ll on[1000001],off[1000001],tog[1000001],noth[1000001];
ll on1[1000001],off1[1000001],tog1[1000001],noth1[1000001];
bool check(ll x)
{
if(x>=0 && x<n)return true;
return false;
}
ll solve(ll index,ll state)
{
ll ans=INF;
if(index>=n)return 0;
if(dp[index][state]!=-1)return dp[index][state];
if(check(on[index]))
{
ans=min(ans,1+solve(on[index]+1,1));
}
if(check(noth[index]))
{
ans=min(ans,solve(noth[index]+1,1));
}
if(check(off[index]))
{
ans=min(ans,1+solve(off[index]+1,1));
}
if(check(tog[index]))
{
ans=min(ans,1+solve(tog[index]+1,1));
}
if(state==1)
{
if(check(on1[index]))
{
ans=min(ans,2+solve(on1[index]+1,2));
}
if(check(noth1[index]))
{
ans=min(ans,1+solve(noth1[index]+1,2));
}
if(check(off1[index]))
{
ans=min(ans,2+solve(off1[index]+1,2));
}
if(check(tog1[index]))
{
ans=min(ans,2+solve(tog1[index]+1,2));
}
}
if(state==2)
{
if(check(on1[index]))
{
ans=min(ans,1+solve(on1[index]+1,2));
}
if(check(noth1[index]))
{
ans=min(ans,solve(noth1[index]+1,2));
}
if(check(off1[index]))
{
ans=min(ans,1+solve(off1[index]+1,2));
}
if(check(tog1[index]))
{
ans=min(ans,1+solve(tog1[index]+1,2));
}
}
/*if(kal[index]==0)
{
if(kal1[index]==kal[index])
{
}
else
{
}
}
else
{
if(kal1[index]==kal[index])
{
}
else
{
}
}*/
return dp[index][state]=ans;
}
ll preprocess(ll arr[])
{
ll fin=-1;
ll deb=-1;
bool ka=false;
for (ll i = 0; i < n; ++i)
{
if(arr[i]==0)
{
if(deb!=-1 && fin!=-1)
{
for (ll j = deb; j <= fin; ++j)
{
arr[j]=fin;
}
}
deb=fin=-1;
ka=false;
arr[i]=-1;
}
else if(!ka)
{
ka=true;
deb=fin=i;
}
else
{
fin++;
}
}
if(deb!=-1)
{
for (ll j = deb; j <= fin; ++j)
{
arr[j]=fin;
}
}
}
int main()
{
flash;
cin>>n;
cin>>kal>>kal1;
memset(dp,-1,sizeof dp);
for (ll i = 0; i < kal.size(); ++i)
{
if(kal[i]=='0')
{
if(kal1[i]==kal[i])
{
off[i]=1;
noth[i]=1;
tog1[i]=1;
on1[i]=1;
}
else
{
on[i]=1;
tog[i]=1;
off1[i]=1;
noth1[i]=1;
}
}
else
{
if(kal1[i]==kal[i])
{
on[i]=1;
noth[i]=1;
tog1[i]=1;
off1[i]=1;
}
else
{
off[i]=1;
tog[i]=1;
on1[i]=1;
noth1[i]=1;
}
}
}
preprocess(off);
preprocess(on);
preprocess(tog);
preprocess(noth);
preprocess(off1);
preprocess(on1);
preprocess(tog1);
preprocess(noth1);
cout<<solve(0,1);
return 0;
}
//code the AC sol !
// BS/queue/map
