부족한 금액 계산하기

using namespace std;

long long solution(int price, int money, int count)
{
    long long answer = 0;// = -1;
    int i;
    
    for(i = 1; i <= count; i++)
    {
        answer += price * i;
    }
    if(answer > money)
    {
        answer = answer - money;
    }
    else
    {
        answer = 0;
    }
    
    return answer;
}