///In the name of GOD
//#pragma GCC optimize("O2")
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MXN = 1e6 + 5;
const ll INF = 1e15;
ll n;
ll dp[MXN][3][2];
string s, t;
int main(){
ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
cin >> n >> s >> t;
s = "$" + s, t = "$" + t;
dp[0][0][0] = 0;
dp[0][0][1] = 1;
dp[0][1][0] = 1;
dp[0][1][1] = 2;
dp[0][2][0] = 1;
dp[0][2][1] = 2;
for(int i = 1; i <= n; i ++){
dp[i][0][0] = dp[i][0][1] = dp[i][1][0] = INF;
dp[i][1][1] = dp[i][2][0] = dp[i][2][1] = INF;
bool f = (s[i] == t[i]);
if(s[i] == t[i]){
dp[i][0][0] = min({dp[i - 1][0][0], dp[i - 1][0][1], dp[i - 1][1][0],
dp[i - 1][1][1], dp[i - 1][2][0], dp[i - 1][2][1]});
}
else{
dp[i][0][1] = min({dp[i - 1][0][0] + 1, dp[i - 1][0][1] + 0, dp[i - 1][1][0] + 1,
dp[i - 1][1][1] + 0, dp[i - 1][2][0] + 1, dp[i - 1][2][1] + 0});
}
f = (t[i] == '1');
if(f){
dp[i][2][0] = min({dp[i - 1][0][0] + 1, dp[i - 1][0][1] + 1, dp[i - 1][1][0] + 1,
dp[i - 1][1][1] + 1, dp[i - 1][2][0] + 0, dp[i - 1][2][1] + 0});
dp[i][1][1] = min({dp[i - 1][0][0] + 2, dp[i - 1][0][1] + 1, dp[i - 1][1][0] + 1,
dp[i - 1][1][1] + 0, dp[i - 1][2][0] + 2, dp[i - 1][2][1] + 1});
}
else{
dp[i][1][0] = min({dp[i - 1][0][0] + 1, dp[i - 1][0][1] + 1, dp[i - 1][1][0] + 0,
dp[i - 1][1][1] + 0, dp[i - 1][2][0] + 1, dp[i - 1][2][1] + 1});
dp[i][2][1] = min({dp[i - 1][0][0] + 2, dp[i - 1][0][1] + 1, dp[i - 1][1][0] + 2,
dp[i - 1][1][1] + 1, dp[i - 1][2][0] + 1, dp[i - 1][2][1] + 0});
}
}
ll ans = min({dp[n][0][0], dp[n][0][1], dp[n][1][0],
dp[n][1][1], dp[n][2][0], dp[n][2][1]});
cout << ans << '\n';
return 0;
}
/*!
HE'S AN INSTIGATOR,
ENEMY ELIMINATOR,
AND WHEN HE KNOCKS YOU BETTER
YOU BETTER LET HIM IN.
*/
//! N.N
