Let's call an undirected graph $G = (V, E)$ relatively prime if and only if for each edge $(v, u) \in E$  $GCD(v, u) = 1$ (the greatest common divisor of $v$ and $u$ is $1$). If there is no edge between some pair of vertices $v$ and $u$ then the value of $GCD(v, u)$ doesn't matter. The vertices are numbered from $1$ to $|V|$.

Construct a relatively prime graph with $n$ vertices and $m$ edges such that it is connected and it contains neither self-loops nor multiple edges.

If there exists no valid graph with the given number of vertices and edges then output "Impossible".

If there are multiple answers then print any of them.


-----Input-----

The only line contains two integers $n$ and $m$ ($1 \le n, m \le 10^5$) — the number of vertices and the number of edges.


-----Output-----

If there exists no valid graph with the given number of vertices and edges then output "Impossible".

Otherwise print the answer in the following format:

The first line should contain the word "Possible".

The $i$-th of the next $m$ lines should contain the $i$-th edge $(v_i, u_i)$ of the resulting graph ($1 \le v_i, u_i \le n, v_i \neq u_i$). For each pair $(v, u)$ there can be no more pairs $(v, u)$ or $(u, v)$. The vertices are numbered from $1$ to $n$.

If there are multiple answers then print any of them.


-----Examples-----
Input
5 6

Output
Possible
2 5
3 2
5 1
3 4
4 1
5 4

Input
6 12

Output
Impossible



-----Note-----

Here is the representation of the graph from the first example: [Image]

Difficulty: interview

Starter code:

Solutions:
from math import *
n, m = list(map(int, input().split()))
if m < n - 1:
    print('Impossible')
    return
r = [(i + 1, i + 2) for i in range(n - 1)]
k = n - 1
if k >= m:
    print('Possible')
    for x in r:
        print(*x)
    return
for i in range(1, n + 1):
    for j in range(i + 2, n + 1):
        if gcd(i, j) == 1:
            r.append((i, j))
            k += 1
        if k >= m:
            print('Possible')
            for x in r:
                print(*x)
            return
print('Impossible')


# def is_prime(n):
#   if n == 2 or n == 3: return True
#   if n < 2 or n%2 == 0: return False
#   if n < 9: return True
#   if n%3 == 0: return False
#   r = int(n**0.5)
#   f = 5
#   while f <= r:
#     if n%f == 0: return False
#     if n%(f+2) == 0: return False
#     f +=6
#   return True
# ans=0
# for i in range(100000):
#     if is_prime(i):
#         ans+=1
#         print(i)
# print(ans)
# print(is_prime(5003))
from math import gcd as bltin_gcd

def cp(a, b):
    return bltin_gcd(a, b) == 1
n,m=[int(x) for x in input().split()]
ans=[]
yes='Possible'
no='Impossible'
def pri():
    print(yes)
    for x in ans:
        print(x[0],' ',x[1])
if m<n-1:
    print(no)
    quit()
if m==n-1:
    print(yes)
    for i in range(1,m+1):
        print(i,' ',i+1)
    quit()
for i in range(1,n):
    ans.append((i,i%n+1))
for i in range(1,n+1):
    for j in range(i+2,n+1):
        if i%2==0 and j%2==0:
            continue
        if cp(i,j):
            ans.append((i,j))
            if len(ans)==m:
                pri()
                quit()
print(no)

# connect!!!


import math
n, m = map(int, input().split())
if m > n * (n - 1) // 2 or m < n - 1:
    print("Impossible");return

rm = m - (n - 1)
ans = [(0, 0)] * (rm * 10)
f = 0

for i in range(3, n+1):
    for j in range(1, i-1):
        if not rm:
            break
        if math.gcd(j, i) == 1:
            ans[f] = (j, i)
            f += 1
            rm -= 1

if rm:
    print('Impossible');return

print('Possible')
for i in range(1, n):
    print(i, i+1)

for i in range(f):
    print(ans[i][0], ans[i][1])