#include <iostream>

int length;
int result;

void remove(int arr[], int left, int right, int size){
    int amount = right - left + 1;
    for (int i = right + 1; i < size; ++i){
        arr[i - amount] = arr[i];
    }
    length -= amount;
    result += amount;
}

int main() {
    int n;
    std::cin >> n;
    length = n;
    int numbers[n];
    for (int i = 0; i < n; ++i){
        std::cin >> numbers[i];
    }

    int del[n];
    int index = 0, flag = 0;

    int length_before = -1;

    while(length_before != length){
        length_before = length;
        flag = 0;
        index = 0;
        for (int i = 1; i < length; ++i){
            if (numbers[i] == numbers[i-1]){
                del[index++] = i - 1;
                flag = 1;
                if (i == length - 1){
                    del[index++] = i;
                    if (del[index - 1] - del[0] + 1 >= 3){
                        remove(numbers, del[0], del[index-1], length);
                        break;
                    }
                    else{
                        flag = 0;
                        index = 0;
                    }
                }
            }
            else{
                if (flag){
                    del[index++] = i - 1;
                    if (del[index - 1] - del[0] + 1 >= 3){
                        remove(numbers, del[0], del[index-1], length);
                        break;
                    }
                    else{
                        flag = 0;
                        index = 0;
                    }

                }
            }
        }
    }

    std::cout << result;




    return 0;
}