#include <iostream>
using namespace std;
const int N = 1<<20;
int dp[N][3];
int main(){
int n;
string a, b;
cin>>n>>a>>b;
for (int i=0;i<N*3;i++)
dp[i / 3][i % 3] = N;
dp[0][2] = 0;
for (int i=1;i<=n;i++){
for (int j : {0, 1, 2}){
char prv = char(j + '0');
if (i > 1 and j == 2)
prv = a[i - 2];
for (int k : {0, 1, 2}){
int cst = dp[i-1][j];
if (j != k and k != 2)
cst++;
char cur = char(k + '0');
if (k == 2)
cur = a[i - 1];
if (cur != b[i-1] and (i == 1 or prv == b[i-2]))
cst++;
if (dp[i][k] > cst)
dp[i][k] = cst;
}
}
}
cout<<min(dp[n][0], min(dp[n][1], dp[n][2]))<<'\n';
}
