#include<bits/stdc++.h>
using namespace std;
const int N = 3e5+10;
int n;
string a,b;
int dp[N][6];
int ans = 1e9;
void Input();
void Dp();
int C(int);
int Esh(int,int);
bool F(char,char,int);
void Output();
int main(){
ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
Input();
Dp();
Output();
}
void Input(){
cin >> n >> a >> b;
}
void Dp(){
//base
for(int i = 0;i < 6;i++)
if(F(a[0], b[0], i))
dp[0][i] = C(i);
else
dp[0][i] = -1;
//dp
for(int i = 1;i < n;i++)
for(int j = 0;j < 6;j++)
if(F(a[i], b[i], j)){
dp[i][j] = n;
for(int k = 0;k < 6;k++)
if(dp[i-1][k] != -1)
dp[i][j] = min(dp[i][j], dp[i-1][k] + C(j) - Esh(k, j));
}else
dp[i][j] = -1;
}
int C(int x){
int res = 0;
if(x > 1) res++;
if(x % 2) res++;
return res;
}
int Esh(int k, int j){
int res = 0;
if(k % 2 and j % 2) res++;
if(k/2 == j/2 and k/2) res++;
return res;
}
bool F(char x,char y,int f){
if((f == 2 or f == 5) and y == '0')
return true;
else if((f == 3 or f == 4) and y == '1')
return true;
else if(f == 0 and x == y)
return true;
else if(f == 1 and x != y)
return true;
return false;
}
void Output(){
for(int i = 0;i < 6;i++)
if(dp[n-1][i] != -1)
ans = min(ans, dp[n-1][i]);
cout << ans << endl;
}
