#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<ll, ll> pii;
typedef pair<ld, ld> pld;
ll n;
ll a[1000009];
ll b[1000009];
ll same[1000009];
ll dp[1000009][2];
string s1, s2;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
cin >> n >> s1 >> s2;
for(ll i = 1; i <= n; ++i)
a[i] = (s1[i-1]-'0');
for(ll i = 1; i <= n; ++i)
b[i] = (s2[i-1]-'0');
for(ll i = 1; i <= n; ++i){
if(i != 1 && b[i-1] == b[i])
same[i] = same[i-1];
else
same[i] = i;
dp[i][0] = dp[i][1] = 1e9;
}
for(ll i = 1; i <= n; ++i){
if(a[i] == b[i]){
dp[i][0] = min(dp[i][0], dp[i-1][0]);
dp[i][1] = min(dp[i][1], 1+min(dp[i-1][1],dp[i-1][0]));
}
else{
dp[i][0] = min(dp[i][0], 1+dp[i-1][0]);
dp[i][1] = min(dp[i][1], min(dp[i-1][1],dp[i-1][0]));
}
dp[i][0] = min(dp[i][0], dp[same[i]-1][0]+1);
dp[i][1] = min(dp[i][1], min(dp[same[i]-1][1], dp[same[i]-1][0])+1);
dp[i][1] = min(dp[i][1], dp[i][0]+1);
dp[i][0] = min(dp[i][0], dp[i][1]+1);
//cout << i << ' ' << dp[i][0] << ' ' << dp[i][1] << '\n';
}
cout << dp[n][0] << '\n';
}
