#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
typedef long long ll;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
const int maxn = 1e6 + 10;
int n;
string a, b;
/**
0 - no operations
1 - set 0 = 0
2 - set 1 = 1
3 - toggle = switch
4 - set 0 toggle = 1
5 - set 1 toggle = 0
*/
const int maxmask = 6;
int path[maxmask][maxmask], to[2][maxmask];
void precompute_masks()
{
to[0][0] = 0;
to[1][0] = 1;
to[0][1] = 0;
to[1][1] = 0;
to[0][2] = 1;
to[1][2] = 1;
to[0][3] = 1;
to[1][3] = 0;
to[0][4] = 1;
to[1][4] = 1;
to[0][5] = 0;
to[1][5] = 0;
path[0][0] = 0;
path[0][1] = 1;
path[0][2] = 1;
path[0][3] = 1;
path[0][4] = 2;
path[0][5] = 2;
path[1][0] = 0;
path[1][1] = 0;
path[1][2] = 1;
path[1][3] = 1;
path[1][4] = 1;
path[1][5] = 2;
path[2][0] = 0;
path[2][1] = 1;
path[2][2] = 0;
path[2][3] = 1;
path[2][4] = 2;
path[2][5] = 1;
path[3][0] = 0;
path[3][1] = 1;
path[3][2] = 1;
path[3][3] = 0;
path[3][4] = 1;
path[3][5] = 1;
path[4][0] = 0;
path[4][1] = 0;
path[4][2] = 1;
path[4][3] = 0;
path[4][4] = 0;
path[4][5] = 1;
path[5][0] = 0;
path[5][1] = 1;
path[5][2] = 0;
path[5][3] = 0;
path[5][4] = 1;
path[5][5] = 0;
}
int dp[maxn][maxmask], f[maxn][maxmask];
void solve()
{
cin >> n >> a >> b;
precompute_masks();
a = "#" + a;
b = "#" + b;
for (int i = 0; i <= n; i ++)
{
for (int mask = 0; mask < maxmask; mask ++)
dp[i][mask] = 1e9, f[i][mask] = -1;
}
dp[0][0] = 0;
for (int i = 1; i <= n; i ++)
{
for (int mask = 0; mask < maxmask; mask ++)
{
if (to[a[i] - '0'][mask] != b[i] - '0')
continue;
for (int from = 0; from < maxmask; from ++)
{
int val = dp[i - 1][from] + path[from][mask];
if (val < dp[i][mask])
{
dp[i][mask] = val;
f[i][mask] = from;
}
}
}
/**cout << "--------------------" << endl;
for (int mask = 0; mask < maxmask; mask ++)
{
cout << dp[i][mask] << " ";
}
cout << endl;
for (int mask = 0; mask < maxmask; mask ++)
{
cout << f[i][mask] << " ";
}
cout << endl;*/
}
int ans = 1e9;
for (int mask = 0; mask < maxmask; mask ++)
ans = min(ans, dp[n][mask]);
cout << ans << endl;
}
int main()
{
speed();
int t = 1;
///cin >> t;
while(t --)
solve();
return 0;
}
