#include "bits/stdc++.h"
using namespace std;
using ll     = long long;
using pii    = pair<int, int>;
using pll    = pair<ll, ll>;
using vi     = vector<int>;
using vl     = vector<ll>;
using vvi    = vector<vi>;
using vvl    = vector<vl>;
const ll INF = 1LL << 60;
const ll MOD = 1000000007;
template <class T>
bool chmax(T &a, const T &b) {
    return (a < b) ? (a = b, 1) : 0;
}
template <class T>
bool chmin(T &a, const T &b) {
    return (b < a) ? (a = b, 1) : 0;
}
template <class C>
void print(const C &c, std::ostream &os = std::cout) {
    std::copy(std::begin(c), std::end(c), std::ostream_iterator<typename C::value_type>(os, " "));
    os << std::endl;
}

int main() {
    int n;
    cin >> n;
    vl a(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }
    if (n == 1) {
        cout << 1 << "\n";
        return 0;
    }
    vi zunda(n, 0);
    for (int i = 1; i < n; ++i) {
        if (a[i] == a[i - 1])
            zunda[i] = 1;
    }
    if (a[1] != 1)
        a[0] = 1;
    for (int i = 1; i < n; ++i) {
        if (i == n - 1 && zunda[i - 1] == 0)
            zunda[i] = 1;
        else if (zunda[i - 1] == 0 && zunda[i] == 0 && zunda[i + 1] == 0)
            zunda[i] = 1;
    }
    int ret = 0;
    for (int i = 0; i < n; ++i) {
        ret += zunda[i];
    }
    cout << ret << "\n";
    return 0;
}