// vaziat meshki-ghermeze !
#include <bits/stdc++.h>
#define pb push_back
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " : " << x << '\n'
using namespace std;
typedef long long ll;
typedef long double ld;
typedef string str;
typedef pair<ll, ll> pll;
const ll Mod = 1000000007LL;
const int N = 2e5 + 10;
const ll Inf = 2242545357980376863LL;
const ll Log = 30;
int dp[4][2];
int nx[4][2];
int main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n;
str A, B;
cin >> n;
cin >> A >> B;
memset(dp, 31, sizeof dp);
dp[0][0] = 0;
for(int i = 0; i < n; i++){
int nw = A[i] - '0';
int rq = B[i] - '0';
memset(nx, 31, sizeof nx);
for(int bl = 0; bl < 4; bl ++) for(int xo = 0; xo < 2; xo ++) for(int set = 0; set < 3; set ++){
int co = set == 2 ? nw : set;
int xxor = co != rq;
int nw_bl = 1;
int la = -1;
if(i > 0){
if(bl > 0)
la = (B[i-1]-'0') ^ xo;
}
if(set == 2) nw_bl = 0;
else {
if(i == 0)
nw_bl = 1;
else
nw_bl = bl + (la != set);
}
bool change = nw_bl != bl;
if(nw_bl == 4)
nw_bl = 2;
nx[nw_bl][xxor] = min(nx[nw_bl][xxor], dp[bl][xo] + (((nw_bl == 1) || (nw_bl == 2)) && change) + (xxor > xo));
}
swap(nx, dp);
}
int ans = n;
for(int i = 0; i < 8; i++)
ans = min(ans, dp[i >> 1][i & 1]);
cout << ans << '\n';
return 0;
}
/*
7
1010010
0000111
4
1010
0000
*/
