[레벨 1] 부족한 금액 계산하기

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>

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