//1L1YA
#include<bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("O3,unrool-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
typedef long long ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
#define Pb push_back
#define F first
#define S second
#define endl '\n'
#define sep ' '
#define all(x) x.begin(),x.end()
#define al(x,n) x+1,x+n+1
#define SZ(x) ((int)x.size())
#define lc (id<<1)
#define rc (lc|1)
#define mid (l+r>>1)
#define dokme(x) cout << x << endl, exit(0)
#define sik(x) cout << x << endl;continue;
#define FastIO ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define FileIO freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll oo=1e18;
const int mod=1e9+7;
const int inf=1e9+111;
const int N=2e5+11;
const int lg=23;
int n;
string a,b;
int main(){
FastIO
cin >> n >> a >> b;
a='#'+a;b='#'+b;
int c=0;
for(int i=1;i<=n;i++)
if(b[i]=='1' && b[i-1]!='1')
c++;
cout << c << endl;
return 0;
}
