#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << " " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << " " << j << " " << #i << " " << q << " " << #p << endl;
#define show4(x,y) for(auto it:y) cout << it << " "; cout << #x << endl;
typedef pair<int,int>pii;
typedef pair<pii,int>pi2;
mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
int n;
string a,b;
int memo[1000005][3][2];
int dp(int index, int cur, int toggle){
if(index==n){
return (cur>0)+(toggle>0);
}
if(memo[index][cur][toggle]!=-1) return memo[index][cur][toggle];
int ans=1e15;
//toggle set
if(b[index]=='1'){
ans=min(ans,dp(index+1,1,1)+(cur==2));
}
else{
ans=min(ans,dp(index+1,2,1)+(cur==1));
}
//toggle no set
if(a[index]!=b[index]){
ans=min(ans,dp(index+1,0,1)+(cur>0));
}
//no toggle set
if(b[index]=='1'){
ans=min(ans,dp(index+1,2,0)+(toggle>0)+(cur==1));
}
else{
ans=min(ans,dp(index+1,1,0)+(toggle>0)+(cur==2));
}
//toggle no set
if(a[index]==b[index]){
ans=min(ans,dp(index+1,0,0)+(cur>0)+(toggle>0));
}
//cout << index << " " << cur << " " << toggle << " " << ans << "\n";
return memo[index][cur][toggle]=ans;
}
void solve(){
cin >> n >> a >> b;
memset(memo,-1,sizeof(memo));
cout << dp(0,0,0);
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
//freopen("in.txt","r",stdin);
//freopen("in.txt","w",stdout);
int t=1;
//cin >> t;
while(t--){
solve();
}
}
