#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define AquA cin.tie(0);ios_base::sync_with_stdio(0);
#define fs first
#define sc second
#define p_q priority_queue
using namespace std;
int main(){
AquA;
int n;
cin >> n;
string a,b;
cin >> a >> b;
vector<array<int,3> > dp(n);
dp[0][0]=1+(0!=b[0]-'0');
dp[0][1]=1+(1!=b[0]-'0');
dp[0][2]=(a[0]!=b[0]);
for(int i=1;i<n;i++){
dp[i][0]=dp[i][1]=dp[i][2]=1e9;
for(int j=0;j<3;j++){
for(int k=0;k<3;k++){
int c=j;
if(c==2){
c=a[i-1]-'0';
}
int d=k;
if(d==2){
d=a[i]-'0';
}
int cnt=0,cz=0;
if(k<=1 && k!=j){
cnt=1;
}
if(d!=b[i]-'0' && c==b[i-1]-'0'){
cz=1;
}
dp[i][k]=min(dp[i][k],dp[i-1][j]+cnt+cz);
}
}
}
cout << min({dp[n-1][0],dp[n-1][1],dp[n-1][2]}) << "\n";
return 0;
}
