Problem:
Score : 100 points

Problem Statement

Snuke has N integers: 1,2,\ldots,N.
He will choose K of them and give those to Takahashi.

How many ways are there to choose K consecutive integers?

Constraints

All values in input are integers.

1 \leq K \leq N \leq 50

Input

Input is given from Standard Input in the following format:

N K

Output

Print the answer.

Sample Input 1

3 2

Sample Output 1

2

There are two ways to choose two consecutive integers: (1,2) and (2,3).

Sample Input 2

13 3

Sample Output 2

11

Solution in Python (3.4.3) (judge verdict: Runtime Error)

n=int(input())
s=list(input() for _ in range(n))
m,o,f,both=0,0,0,0

for i in range(n):
    m +=s[i].count("AB")
    if s[i][0]=="B":
        o +=1
for i in range(n):
    if s[i][-1]=="A":
        f +=1
for i in range(n):
    if s[i][0]=="B" and s[i][-1]=="A":
        both+=1
        o-=1
        f-=1

if both!=0:
    if i!=0 and f!=0:
        print(m+both+min(o,f))
    else:
        print(m+both+min(o,f)-1)

else:
    print(m+min(o,f))