#include <bits/stdc++.h>
#define fr(i, n, m) for(int i = (n); i < (m); i ++)
#define pb push_back
#define st first
#define nd second
#define pq priority_queue
#define all(x) begin(x), end(x)
#include <time.h>
#include <cmath>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const int i_inf = 1e9;
const ll inf = 1e18;
const ll mod = 1000000007;
const ld eps = 1e-13;
const ld pi = 3.14159265359;
mt19937 _rand(time(NULL));
clock_t timer = clock();
const int mxn = 5e5;
const ll A = 911382323;
const ll B = 972663749;
ll modpow(ll x, ll n){
if(n == 0) return 1%mod;
ll u = modpow(x, n/2);
u = (u * u) % mod;
if(n % 2) u = (u * x) % mod;
return u;
}
ll inverse(ll x){
return modpow(x, mod-2);
}
ll add(ll ans, ll val){
ans = (ans + val) % mod;
return ans;
}
ll mul(ll ans, ll val){
ans = (ans * val) % mod;
return ans;
}
ll sub(ll ans, ll val){
ans = (ans - val) % mod;
if(ans < 0) ans += mod;
return ans;
}
ll _div(ll ans, ll val){
ans = (ans * inverse(val)) % mod;
return ans;
}
ll fakt[mxn];
ll bc(ll n, ll k){
return (fakt[n]*inverse((fakt[k]*fakt[n-k])%mod))%mod;
}
ll sq(ll x){
return x*x;
}
ll rsum(ll a, ll b){
return (b-a+1)*(a+b)/2;
}
void prec(){
fakt[0] = 1;
fr(i, 1, mxn){
fakt[i] = mul(fakt[i-1], i);
}
}
int dp[mxn][6];
int trans[6][6];
void solve(){
int val[6] = {0, 1, 2, 4, 5, 6};
fr(i, 0, 6) fr(j, 0, 6) trans[i][j] = __builtin_popcount((val[i]|val[j])^val[i]);
int n;
cin >> n;
string a, b;
cin >> a;
cin >> b;
fr(i, 0, n+1)fr(j, 0, 6) dp[i][j] = i_inf;
dp[0][0] = 0;
fr(i, 1, n+1){
if(a[i-1] == '1' && b[i-1] == '1'){
fr(pr, 0, 6){
dp[i][0] = min(dp[i][0], dp[i-1][pr] + trans[pr][0]);
dp[i][1] = min(dp[i][1], dp[i-1][pr] + trans[pr][1]);
dp[i][5] = min(dp[i][5], dp[i-1][pr] + trans[pr][5]);
}
}
else if(a[i-1] == '0' && b[i-1] == '0'){
fr(pr, 0, 6){
dp[i][0] = min(dp[i][0], dp[i-1][pr] + trans[pr][0]);
dp[i][2] = min(dp[i][2], dp[i-1][pr] + trans[pr][2]);
dp[i][4] = min(dp[i][4], dp[i-1][pr] + trans[pr][4]);
}
}
else if(a[i-1] == '1' && b[i-1] == '0'){
fr(pr, 0, 6){
dp[i][2] = min(dp[i][2], dp[i-1][pr] + trans[pr][2]);
dp[i][3] = min(dp[i][3], dp[i-1][pr] + trans[pr][3]);
dp[i][4] = min(dp[i][4], dp[i-1][pr] + trans[pr][4]);
}
}
else if(a[i-1] == '0' && b[i-1] == '1'){
fr(pr, 0, 6){
dp[i][1] = min(dp[i][1], dp[i-1][pr] + trans[pr][1]);
dp[i][3] = min(dp[i][3], dp[i-1][pr] + trans[pr][3]);
dp[i][5] = min(dp[i][5], dp[i-1][pr] + trans[pr][5]);
}
}
}
int ans = i_inf;
fr(i, 0, 6) ans = min(ans, dp[n][i]);
cout<<ans<<endl;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
solve();
}
