#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
using ll = long long;
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#define MAX(a, b) (((a) < (b)) ? (b) : (a))
int const nmax = 1000005;
int v[1 + nmax], v2[1 + nmax];
string s;
int dp[1 + nmax][3];
int extract(int x, int state){
if(state == 2)
return v[x] ^ v2[x];
else
return state ^ v2[x];
}
int main()
{
int n;
cin >> n;
cin >> s;
s = "#" + s;
for(int i = 1; i <= n;i++)
v[i] = s[i] - '0';
cin >> s;
s = "#" + s;
for(int i = 1; i <= n;i++)
v2[i] = s[i] - '0';
dp[0][0] = dp[0][1] = nmax;
dp[0][2] = 0;
for(int i = 1;i <= n; i++){
dp[i][0] = min(dp[i - 1][0] + (extract(i - 1, 0) ^ extract(i, 0)), dp[i - 1][2] + 2 + (extract(i - 1, 2) ^ extract(i, 0)));
dp[i][1] = min(dp[i - 1][1] + (extract(i - 1, 1) ^ extract(i, 1)), dp[i - 1][2] + 2 + (extract(i - 1, 2) ^ extract(i, 1)));
dp[i][2] = min(dp[i - 1][2] + (extract(i - 1, 2) ^ extract(i, 2)),
min(dp[i - 1][0] + (extract(i - 1, 0) ^ extract(i, 2)),
dp[i - 1][1] + (extract(i - 1, 1) ^ extract(i, 2))
));
}
cout << (min(dp[n][0], min(dp[n][1], dp[n][2])) + 1) / 2;
return 0;
}
