#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int n;
cin>>n;
string s,t;
cin>>s>>t;
int a[n+5],b[n+5];
for(int i=1;i<=n;i++){
a[i]=(s[i-1]-'0');
b[i]=(t[i-1]-'0');
}
int dp[n+5][3];
dp[0][0]=0;
dp[0][1]=dp[0][2]=1e9;
//dp[i][j]=x+y, x-set range, y-flip range
for(int i=1;i<=n;i++){
for(int j=0;j<3;j++) dp[i][j]=1e9;
for(int j=0;j<3;j++){
for(int k=0;k<3;k++){
int bef=0;//1-same,0-dif
int now=0;
if(i==1) bef=1;
else{
if(j==0) bef=(a[i-1]==b[i-1]?1:0);
else if(j==1) bef=(b[i-1]==0?1:0);
else bef=(b[i-1]==1?1:0);
}
if(k==0) now=(a[i]==b[i]?1:0);
else if(k==1) now=(b[i]==0?1:0);
else now=(b[i]==1?1:0);
dp[i][k]=min(dp[i][k],dp[i-1][j]+(k!=0&&k!=j)+(bef==1&&now==0));
}
}
}
cout<<min({dp[n][0],dp[n][1],dp[n][2]});
}
