Doubt in the BUS full of passengers in codechef starters 9 (Div 3 )

This is my code for the question, test cases are all passed, when i submit i am getting wrong answer. The code mentioned in the editorial is also same. but i don’t understand where my code is failing.

can anyone provide a test case where my code fails or let me know if there is any logical error in my code.

here is the code

bool solve()

{

    int n, m, q;

    cin >> n >> m >> q;

    int arr[n+1] = {0};

    char ch;

    int i, count = 0;

    for (int j = 1; j <= q; j++)

    {

        cin >> ch;

        cin >> i;

        if (ch == '+')

        {

            if (arr[i] == 0)

            {

                count++;

                arr[i] = 1;

            }

            else

                return false;

        } 

        if (ch == '-')

        {

            if (arr[i] == 1)

                count--;

            else

                return false;

        }

        if (count > m)

            return false;

    }

    return true;

}