#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MAXN = 1e6+1;
int dp[MAXN][2][3];
signed main(void)
{
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int nbCarac;
cin >> nbCarac;
string have, want;
cin >> have >> want;
vector<bool> from(nbCarac), to(nbCarac);
for (int iCarac(0); iCarac < nbCarac; ++iCarac)
from[iCarac] = have[iCarac] - '0', to[iCarac] = want[iCarac] - '0';
for (int i(0); i < MAXN; ++i)
for (int j(0); j < 2; ++j)
for (int k(0); k < 3; ++k)
dp[i][j][k] = 1e9;
dp[0][0][2] = 0;
for (int nbVus(1); nbVus <= nbCarac; ++nbVus)
for (int flip(0); flip < 2; ++flip)
for (int set(0); set < 3; ++set)
if ( (set == 2 and (from[nbVus-1] ^ flip) == to[nbVus-1])
or (set != 2 and (set ^ flip) == to[nbVus-1]))
{
int &cur = dp[nbVus][flip][set];
for (int prvFlip(0); prvFlip < 2; ++prvFlip)
for (int prvSet(0); prvSet < 3; ++prvSet)
{
int cost = (!prvFlip and flip) + (set != 2 and set != prvSet);
cur = min(cur, cost + dp[nbVus-1][prvFlip][prvSet]);
}
}
int ret = 1e9;
for (int i(0); i < 2; ++i)
for (int j(0); j < 3; ++j)
ret = min(ret, dp[nbCarac][i][j]);
cout << ret << endl;
}
