#include <bits/stdc++.h>
using namespace std;
int const NMAX=1000005;
bool sir1[NMAX],sir2[NMAX];
int dp[NMAX][3];
int n;
void read(){
cin>>n;
int i;
char ch;
for(i=1;i<=n;++i){
cin>>ch;
sir1[i]=ch-'0';
}
for(i=1;i<=n;++i){
cin>>ch;
sir2[i]=ch-'0';
}
}
void minself(int& x,int val){
if(x>val)
x=val;
}
int const INF=1e9;
int get_dp(){
dp[1][0]=1+(sir2[1]!=0);
dp[1][1]=1+(sir2[1]!=1);
dp[1][2]=(sir1[1]!=sir2[1]);
int i,j,k;
for(i=2;i<=n;++i)
for(j=0;j<3;++j){
dp[i][j]=INF;
int vj=((j==2)?sir1[i]:j);
for(k=0;k<3;++k){
int vk=((k==2)?sir1[i-1]:k);
minself(dp[i][j],dp[i-1][k]+(j<2 && j!=k)+(vk==sir2[i-1] && vj!=sir2[i]));
}
}
return min(min(dp[n][0],dp[n][1]),dp[n][2]);
}
int main()
{
read();
cout<<get_dp();
return 0;
}
