#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
double cur = rngesus(0, MASK(60) - 1);
cur /= MASK(60) - 1;
return l + cur * (r - l);
}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
int n;
string s1, s2;
int dp[2][16];
const int INF = 1e9 + 69;
int main(void){
ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
clock_t start = clock();
vector<vector<int>> S;
vector<int> perm(3);
for(int i = 0; i<3; ++i) perm[i] = i;
do{
vector<int> cur;
for(int i: perm){
cur.push_back(i);
S.push_back(cur);
}
} while(next_permutation(ALL(perm)));
S.push_back({});
remove_dup(S);
int kost[S.size()][S.size()];
for(int i = 0; i < (int)S.size(); ++i) for(int j = 0; j < (int)S.size(); ++j){
vector<int> s1 = S[i], s2 = S[j];
int x = s1.size(), y = s2.size();
int dp[x+1][y+1];
memset(dp, 0, sizeof dp);
for(int i = 1; i<=x; ++i) for(int j = 1; j<=y; ++j){
dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
if (s1[i-1] == s2[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
}
kost[i][j] = s2.size() - dp[x][y];
}
int transition[S.size()][2];
for(int i = 0; i < (int)S.size(); ++i) for(int j = 0; j <= 1; ++j){
int cur =j;
for(int k: S[i]){
if (k == 0) cur ^= 1;
if (k == 1) cur = 0;
if (k == 2) cur = 1;
}
transition[i][j] = cur;
}
cin >> n;
cin >> s1 >> s2;
s1 = "0" + s1;
s2 = "0" + s2;
fill(dp[0], dp[1] + 16, INF);
dp[0][0] = 0;
for(int i = 1; i<=n; ++i){
int digit1 = s1[i] - '0', digit2 = s2[i] - '0';
for(int j = 0; j < 16; ++j) if (dp[0][j] != INF) {
for(int k = 0; k < 16; ++k) if (transition[k][digit1] == digit2){
minimize(dp[1][k], dp[0][j] + kost[j][k]);
}
}
for(int j = 0; j < 16; ++j){
// if (dp[1][j] != INF) cout << i << " " << j << " " << dp[1][j] << "\n";
dp[0][j] = dp[1][j];
dp[1][j] = INF;
}
}
int ans = INF;
for(int i = 0; i<16; ++i) minimize(ans, dp[0][i]);
cout << ans << "\n";
cerr << "Time elapsed: " << clock() - start << " ms\n";
return 0;
}
