#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
typedef long long ll;
const int N = 1e6+5;
int n, dp[N][5], nxt[N];
string a, b;
void operate()
{
int one = n, zero = n;
for(int i=n-1; i>=0; i--)
{
if(b[i] == '1') one = i, nxt[i] = zero;
else zero = i, nxt[i] = one;
}
}
int sol(int i, int t)
{
if(i == n) return 0;
int &ret = dp[i][t];
if(ret != -1) return ret;
ret = sol(nxt[i], t)+1;
if(t == 2 && nxt[i] != n)
{
if(b[i] == '0') ret = min(ret, sol(nxt[i], 1)+1);
else ret = min(ret, sol(nxt[i], 0)+1);
}
if((t == 1 && b[i] == '0') || (t == 0 && b[i] == '1'))
ret = min(ret, sol(nxt[i], 2)+1);
if(t == 3)
{
if(a[i] == b[i]) ret = min(ret, sol(i+1, t));
else if(b[i] == '0') ret = min(ret, min(sol(i+1, 2), sol(i+1, 0))+1);
else ret = min(ret, min(sol(i+1, 2), sol(i+1, 1))+1);
}
if(t == 2)
{
if(a[i] == b[i]) ret = min(ret, sol(i+1, 3));
else ret = min(ret, sol(i+1, t));
}
if(t == 1)
{
if(b[i] == '1') ret = min(ret, sol(i+1, t));
else if(b[i] == a[i]) ret = min(ret, sol(i+1, 3));
else ret = min(ret, min(sol(i+1, 2), sol(i+1, 0))+1);
}
if(!t)
{
if(b[i] == '0') ret = min(ret, sol(i+1, t));
else if(a[i] == b[i]) ret = min(ret, sol(i+1, 3));
else ret = min(ret, min(sol(i+1, 2), sol(i+1, 1))+1);
}
return ret;
}
int main()
{
memset(dp, -1, sizeof dp);
cin >> n >> a >> b;
operate();
cout << sol(0, 3) << endl;
}
