#include<iostream>
#include<stdio.h>
#include<vector>
#include<cmath>
#include<queue>
#include<string.h>
#include<unordered_map>
#include<set>
#include<algorithm>
#define ll int
#define pi pair < ll,ll >
#define mp(a,b) make_pair(a,b)
#define mid (low+high)/2
#define rep(i,a,b) for(int i = a;i < b;i++)
#define N 1000004
#define INF 1000004
using namespace std;
ll n;
string s,t;
int dp[N][6];
/* 0: den ekana operation sto i, 1: kame to i set se 1, 2: kame to i set se 0,
3:kame to i toggle, 4: kame to i 1 kai meta toggle, 5: kame to i 0 kai meta toggle
*/
void solve()
{
if(s[0]==t[0])
{
dp[0][0] = 0;
dp[0][3] = INF;
}
else
{
dp[0][0] = INF;
dp[0][3] = 1;
}
if(t[0] == '0')
{
dp[0][2] = 1;
dp[0][1] = INF;
dp[0][4] = 2;
dp[0][5] = INF;
}
else
{
dp[0][1] = 1;
dp[0][2] = INF;
dp[0][4] = INF;
dp[0][5] = 2;
}
rep(i,1,n)
{
if(s[i] == t[i])
{
dp[i][0] = min(dp[i-1][0],dp[i-1][1]);
dp[i][0] = min(dp[i][0],dp[i-1][2]);
dp[i][0] = min(dp[i][0],dp[i-1][3]);
dp[i][0] = min(dp[i][0],dp[i-1][4]);
dp[i][0] = min(dp[i][0],dp[i-1][5]);
dp[i][3] = INF;
}
else
{
dp[i][0] = INF;
dp[i][3] = min(dp[i-1][0]+1,dp[i-1][1]+1);
dp[i][3] = min(dp[i][3],dp[i-1][2]+1);
dp[i][3] = min(dp[i][3],dp[i-1][3]);
dp[i][3] = min(dp[i][3],dp[i-1][4]);
dp[i][3] = min(dp[i][3],dp[i-1][5]);
}
if(t[i] == '1')
{
dp[i][2] = INF;
dp[i][1] = min(dp[i-1][0]+1,dp[i-1][1]);
dp[i][1] = min(dp[i][1],dp[i-1][2]+1);
dp[i][1] = min(dp[i][1],dp[i-1][3]+1);
dp[i][1] = min(dp[i][1],dp[i-1][4]);
dp[i][1] = min(dp[i][1],dp[i-1][5]+1);
dp[i][4] = INF;
dp[i][5] = min(dp[i-1][0]+2,dp[i-1][1]+2);
dp[i][5] = min(dp[i][5],dp[i-1][2]+1);
dp[i][5] = min(dp[i][5],dp[i-1][3]+1);
dp[i][5] = min(dp[i][5],dp[i-1][4]+1);
dp[i][5] = min(dp[i][5],dp[i-1][5]);
}
else
{
dp[i][1] = INF;
dp[i][2] = min(dp[i-1][0]+1,dp[i-1][2]);
dp[i][2] = min(dp[i][2],dp[i-1][1]+1);
dp[i][2] = min(dp[i][2],dp[i-1][3]+1);
dp[i][2] = min(dp[i][2],dp[i-1][4]+1);
dp[i][2] = min(dp[i][2],dp[i-1][5]);
dp[i][5] = INF;
dp[i][4] = min(dp[i-1][0]+2,dp[i-1][2]+2);
dp[i][4] = min(dp[i][4],dp[i-1][1]+1);
dp[i][4] = min(dp[i][4],dp[i-1][3]+1);
dp[i][4] = min(dp[i][4],dp[i-1][4]);
dp[i][4] = min(dp[i][4],dp[i-1][5]+1);
}
}
return;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
cin >> s;
cin >> t;
solve();
cout << min({dp[n-1][0],dp[n-1][1],dp[n-1][2],dp[n-1][3],dp[n-1][4],dp[n-1][5]});
return 0;
}
