#include <bits/stdc++.h>
#include <bits/extc++.h>
#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define ef(a) emplace_front(a)
#define pob pop_back()
#define pof pop_front()
#define mp(a, b) make_pair(a, b)
#define F first
#define S second
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define iceil(a, b) (((a) + (b) - 1) / (b))
#define tomax(a, b) ((a) = max((a), (b)))
#define tomin(a, b) ((a) = min((a), (b)))
#define topos(a) ((a) = (((a) % MOD + MOD) % MOD))
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
if(pvaspace) b << " "; pvaspace=true;\
b << pva;\
}\
b << "\n";}
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using tiii = tuple<int, int, int>;
const ll MOD = 1000000007;
const ll MAX = 2147483647;
template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
return o << '(' << p.F << ',' << p.S << ')';
}
int main(){
StarBurstStream
int n;
cin >> n;
string a, b;
cin >> a >> b;
a = '0' + a + '0';
b = '0' + b + '0';
vector<ll> dp(3, MAX);
dp[0] = 0;
for(int i = 1; i <= n + 1; i++){
// cerr << "test " << i << "\n";
vector<ll> dp2(3, MAX);
for(int j = 0; j < 3; j++){
int now;
if(j & 1) now = '0' != b[i];
else if(j & 2) now = '1' != b[i];
else now = a[i] != b[i];
for(int k = 0; k < 3; k++){
int lst;
if(k & 1) lst = '0' != b[i - 1];
else if(k & 2) lst = '1' != b[i - 1];
else lst = a[i - 1] != b[i - 1];
// cerr << j << " " << k << " " << now << " " << lst << "\n";
dp2[j] = min(dp2[j], dp[k] + (now != lst) + (j != k ? !!k + !!j : 0));
}
}
dp = dp2;
// cerr << i << " ";
// printv(dp, cerr);
}
cout << dp[0] / 2 << "\n";
return 0;
}
