## CCC '20 J2 - Epidemiology

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Points: 3
Time limit: 1.0s
Python 3 3.0s
Memory limit: 512M

Problem type
##### Canadian Computing Competition: 2020 Stage 1, Junior #2

People who study epidemiology use models to analyze the spread of disease. In this problem, we use a simple model.

When a person has a disease, they infect exactly other people but only on the very next day. No person is infected more than once. We want to determine when a total of more than people have had the disease.

(This problem was designed before the current coronavirus outbreak, and we acknowledge the distress currently being experienced by many people worldwide because of this and other diseases. We hope that including this problem at this time highlights the important roles that computer science and mathematics play in solving real-world problems.)

#### Input Specification

There are three lines of input. Each line contains one positive integer. The first line contains the value of . The second line contains , the number of people who have the disease on Day . The third line contains the value of . Assume that and and .

#### Output Specification

Output the number of the first day on which the total number of people who have had the disease is greater than .

#### Sample Input 1

750
1
5

#### Output for Sample Input 1

4

#### Explanation of Output for Sample Input 1

The person on Day with the disease infects people on Day . On Day , exactly other people are infected. On Day , exactly other people are infected. A total of people have had the disease by the end of Day and .

#### Sample Input 2

10
2
1

#### Output for Sample Input 2

5

#### Explanation of Output for Sample Input 2

There are people on Day with the disease. On each other day, exactly other people are infected. By the end of Day , a total of exactly people have had the disease and by the end of Day , more than people have had the disease.

• commented on Feb. 24, 2024, 1:21 a.m.

Heute bin ich dran

• commented on Jan. 15, 2024, 1:39 a.m.

I use ChatGPT to walk me through the process for CCC problems while practicing, but ChatGPT seems to really struggle to understand this one.

• commented on Jan. 12, 2024, 10:27 a.m.

Interesting problem and surprisingly more difficult to solve than I expected it to be.

• commented on Feb. 22, 2022, 1:10 a.m.

Only in Canada will you have contest organizers apologize for a pandemic that they didn't know would happen.

• commented on Feb. 22, 2022, 1:38 a.m.

meanwhile USACO made COWVID-19 themed problems

• commented on Feb. 21, 2022, 9:42 p.m.

An important lesson I have learned. Don't forget to delete the code you write to check new values.

I lost half an hour trying to find out why my answer was correct, and then I noticed I had some print statements to check the values.

• commented on Oct. 10, 2020, 1:53 a.m. edited

It's a very interesting challenge though.

• commented on April 3, 2020, 7:59 p.m.

This question was surprisingly difficult compared to the other questions during this years contest

• commented on April 3, 2020, 9:42 p.m.

This comment is hidden due to too much negative feedback. Show it anyway.