#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pii;
#define fi first
#define se second
#define mp make_pair
#define fastIO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
const int N = (int)1e6 + 9;
int dp[N][3][2];
int main(){
fastIO;
int n;
cin >> n;
for(int i = 0 ; i < N ;i ++ ){
for(int j = 0 ; j < 3 ; j ++ )
for(int z = 0; z < 2 ;z ++ )
dp[i][j][z] = 12124141;
}
string a, b;
cin >> a >> b;
int from, to;
int nw;
int sum;
dp[0][0][0] = 0;
for(int i = 1 ; i <= n; i ++ ){
from = a[i-1] - '0';
to = b[i-1] - '0';
for(int j = 0 ; j < 3; j ++ ){
for(int z = 0 ;z < 2; z ++ ){
nw = from;
if(j) nw = j - 1;
if(z) nw ^= 1;
if(nw == to){
for(int v = 0; v < 3 ;v ++ ){
for(int q = 0 ;q < 2; q ++ ){
sum = dp[i-1][v][q];
if(j > 0 && j != v) sum ++ ;
if(z > 0 && z != q) sum ++ ;
dp[i][j][z] = min(dp[i][j][z], sum);
}
}
}
}
}
}
int res = 124214124;
for(int i = 0 ; i < 3; i ++ )
for(int j = 0 ; j < 2; j ++ ){
res = min(res, dp[n][i][j]);
}
cout << res;
return 0;
}
