#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<ll, ll>
#define fi first
#define sec second
#define ld long double
const int MAXN = 1e6;
const ll INF = 1e18;
const int MOD = 1e9 + 7;
ll dp[MAXN + 5][4][4];
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int tc = 1;
// cin >> tc;
for(;tc--;){
ll N; cin >> N;
string A, B; cin >> A >> B;
A = '%' + A, B = '$' + B;
for(int i = 0; i <= N; i++){
for(int j = 0; j < 3; j++){
for(int k = 0; k < 2; k++) dp[i][j][k] = INF;
}
}
dp[0][0][0] = 0;
for(int i = 1; i <= N; i++){
for(int j = 0; j < 3; j++){
for(int k = 0; k < 2; k++){
if(B[i] == '1'){
dp[i][1][0] = min(dp[i][1][0], dp[i - 1][j][k] + (j != 1));
dp[i][2][1] = min(dp[i][2][1], dp[i - 1][j][k] + (j != 2) + (k != 1));
}
if(B[i] == '0'){
dp[i][1][1] = min(dp[i][1][1], dp[i - 1][j][k] + (j != 1) + (k != 1));
dp[i][2][0] = min(dp[i][2][0], dp[i - 1][j][k] + (j != 2));
}
if(A[i] == B[i]){
dp[i][0][0] = min(dp[i][0][0], dp[i - 1][j][k]);
}
if(A[i] != B[i]){
dp[i][0][1] = min(dp[i][0][1], dp[i - 1][j][k] + (k != 1));
}
}
}
}
ll ans = INF;
for(int i = 0; i < 3; i++){
for(int j = 0; j < 2; j++) ans = min(ans, dp[N][i][j]);
}
cout << ans << "\n";
}
}
/*
dp[j] + 1 + (ps[i] - ps[j])
*/
