Problem: We have N boxes, numbered 1 through N. At first, box 1 contains one red ball, and each of the other boxes contains one white ball.

Snuke will perform the following M operations, one by one. In the i-th operation, he randomly picks one ball from box x_i, then he puts it into box y_i.

Find the number of boxes that may contain the red ball after all operations are performed.

Constraints

* 2≤N≤10^5
* 1≤M≤10^5
* 1≤x_i,y_i≤N
* x_i≠y_i
* Just before the i-th operation is performed, box x_i contains at least 1 ball.

Input

The input is given from Standard Input in the following format:


N M
x_1 y_1
:
x_M y_M


Output

Print the number of boxes that may contain the red ball after all operations are performed.

Examples

Input

3 2
1 2
2 3


Output

2


Input

3 3
1 2
2 3
2 3


Output

1


Input

4 4
1 2
2 3
4 1
3 4


Output

3

Solution (in PYTHON3):

Solution:
n,m = map(int, input().split())
r = [0]*(n+1)
r[1] = 1
b0 = [1]*(n+1)
for i in range(m):
    x,y = map(int, input().split())
    b0[x] -= 1
    b0[y] += 1
    if r[x]:
        r[y] = 1
    if b0[x]==0:
        r[x]=0
ans = 0
for j in range(n+1):
    if r[j]:
        ans += 1
print(ans)