#include<iostream>
#include<stdio.h>
#include<vector>
#include<cmath>
#include<queue>
#include<string.h>
#include<unordered_map>
#include<set>
#include<algorithm>
#define ll int
#define pi pair < ll,ll >
#define mp(a,b) make_pair(a,b)
#define mid (low+high)/2
#define rep(i,a,b) for(int i = a;i < b;i++)
#define N 300004
#define INF 1e9+7
using namespace std;
ll n;
string s,t;
bool vis[N];
int steps[N];
void solve()
{
queue < int > q;
int ss = 0;
rep(i,0,n)
ss += (s[i]-'0')*(1 << i);
q.push(ss);
vis[ss]=true;
steps[ss] = 0;
while(!q.empty())
{
int cur = q.front();
q.pop();
int tmp = cur;
rep(i,0,n)
{
tmp = cur;
rep(j,i,n)
{
tmp |= (1 << j);
if(!vis[tmp])
{
vis[tmp]=true;
steps[tmp]=steps[cur]+1;
q.push(tmp);
}
}
}
rep(i,0,n)
{
tmp = cur;
rep(j,i,n)
{
tmp &= ~(1 << j);
if(!vis[tmp])
{
vis[tmp]=true;
steps[tmp]=steps[cur]+1;
q.push(tmp);
}
}
}
rep(i,0,n)
{
tmp = cur;
rep(j,i,n)
{
tmp ^= (1 << j);
if(!vis[tmp])
{
vis[tmp]=true;
steps[tmp]=steps[cur]+1;
q.push(tmp);
}
}
}
}
return;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
cin >> s;
cin >> t;
solve();
int tt=0;
rep(i,0,n)
tt += (t[i]-'0')*(1<<i);
cout << steps[tt];
return 0;
}
