N, M = list(map(int, input().split()))

AB = [list(map(int, input().split())) for _ in range(M)]



s, e = set(), set()

for ab in AB:

    a, b = ab

    if a == 1:

        s.add(b)

    elif b == N:

        e.add(a)

if len(s & e) >= 1:

    print('POSSIBLE')

else:

    print('IMPOSSIBLE')

import sys

input = sys.stdin.readline

N, M = list(map(int, input().split()))

AB = [list(map(int, input().split())) for _ in range(M)]



s, e = set(), set()

for ab in AB:

    a, b = ab

    if a == 1:

        s.add(b)

    elif b == N:

        e.add(a)

if len(s & e) >= 1:

    print('POSSIBLE')

else:

    print('IMPOSSIBLE')

N, M = list(map(int, input().split()))
AB = [list(map(int, input().split())) for _ in range(M)]
s, e = set(), set()
for ab in AB:
    a, b = ab
    if a == 1:
        s.add(b)
    elif b == N:
        e.add(a)
if len(s & e) >= 1:
    print("POSSIBLE")
else:
    print("IMPOSSIBLE")

import sys

input = sys.stdin.readline
N, M = list(map(int, input().split()))
AB = [list(map(int, input().split())) for _ in range(M)]
s, e = set(), set()
for ab in AB:
    a, b = ab
    if a == 1:
        s.add(b)
    elif b == N:
        e.add(a)
if len(s & e) >= 1:
    print("POSSIBLE")
else:
    print("IMPOSSIBLE")

+import sys + +input = sys.stdin.readline