Problem:
Score : 100 points

Problem Statement

We have two bottles for holding water.

Bottle 1 can hold up to A milliliters of water, and now it contains B milliliters of water.

Bottle 2 contains C milliliters of water.

We will transfer water from Bottle 2 to Bottle 1 as much as possible.

How much amount of water will remain in Bottle 2?

Constraints

All values in input are integers.

1 \leq B \leq A \leq 20

1 \leq C \leq 20

Input

Input is given from Standard Input in the following format:

A B C

Output

Print the integer representing the amount of water, in milliliters, that will remain in Bottle 2.

Sample Input 1

6 4 3

Sample Output 1

1

We will transfer two milliliters of water from Bottle 2 to Bottle 1, and one milliliter of water will remain in Bottle 2.

Sample Input 2

8 3 9

Sample Output 2

4

Sample Input 3

12 3 7

Sample Output 3

0

Solution in Ruby (2.3.3) (judge verdict: Runtime Error)

n=gets.to_i
h=gets.split.map(:to_i)
ans="Yes"
i=0
flg=0
while i<n
  d=h[i+1]-h[i]
  if d==2
    h[i+1]-=1
    flg=1
  elsif d==1
    flg=0
  elsif d==-1
    if flg==1
      ans="No"
      break
    else
      mrk=true
    end
  elsif d==0
  else
    ans="No"
    break
  end
  i+=1
end
puts ans