#include <iostream>
#include <cmath>

using namespace std;
int main()
{
    int N, l, d, i, j, count=1;
    int a[2020];
    bool b = false;
    cin >> N;
    d = N  ;
    for (i = 0; i < 2020; i++)
        a[i] = -1;

    for (i = 0; i < N; i++){
        cin >> a[i];
    }

    for (i = 0; i < N; i++)
        if (a[i] == a[i+1]) {
            count++;
            if (count > 2) j = i;
        }
        else if (count > 2) {
            b = true;
            break;
        }
        else {
            count = 1;
        }
    while (b && N>0){
        for (i=j - count + 2; i < N - count ; i++)
            a[i] = a[i+count];
        N = N-count;
        a[N] = -1;
        count = 1;

        for (i = 0; i < N; i++)
            if (a[i] == a[i+1]) {
                count++;
                if (count > 2) j = i;
            }
            else if (count > 2) {
                b = true;
                break;
            }
            else {
                count = 1;
                b = false;
            }
    }
    cout << d - N;
}