#include<bits/stdc++.h>
using namespace std;
const int maxn=1000000+10;
int dp[maxn][2][3],inf=maxn+10;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n;
string s,ss;
cin>>n>>s>>ss;
for(int i=0;i<2;i++){
for(int j=0;j<3;j++){
dp[0][i][j]=inf;
}
}
dp[0][0][2]=0;
for(int ind=1;ind<=n;ind++){
for(int i=0;i<2;i++){
for(int j=0;j<2;j++){
dp[ind][i][j]=min(dp[ind-1][i^1][j]+(i==1),min(dp[ind-1][i^1][j^1]+(i==1),dp[ind-1][i^1][2]+(i==1))+1);
dp[ind][i][j]=min(dp[ind-1][i][j],min(dp[ind-1][i][j^1],dp[ind-1][i][2])+1);
}
dp[ind][i][2]=min(dp[ind-1][i][0],min(dp[ind-1][i][1],dp[ind-1][i][2]));
dp[ind][i][2]=min(dp[ind][i][2],min(dp[ind-1][i^1][0],min(dp[ind-1][i^1][1],dp[ind-1][i^1][2]))+(i==1));
}
if(s[ind-1]==ss[ind-1]){
dp[ind][0][(s[ind-1]-'0')^1]=inf;
dp[ind][1][(s[ind-1]-'0')]=inf;
dp[ind][1][2]=inf;
}
else{
dp[ind][0][(s[ind-1]-'0')]=inf;
dp[ind][0][2]=inf;
dp[ind][1][(s[ind-1]-'0')^1]=inf;
}
// cout<<"injy: "<<ind<<"\n";
// for(int i=0;i<2;i++){
// for(int j=0;j<3;j++){
// cout<<dp[ind][i][j]<<" ";
// }
// cout<<"\n";
// }
// cout<<"\n";
}
long long res=min(dp[n][0][0],min(dp[n][0][1],min(dp[n][0][2],min(dp[n][1][0],min(dp[n][1][1],dp[n][1][2])))));
cout<<res<<"\n";
}
