# 2019/08/05



n,m=list(map(int,input().split()))

edge=[[] for _ in range(n)]

for i in range(m):

    a,b=list(map(int,input().split()))

    a-=1;b-=1

    edge[a].append(b)

    edge[b].append(a)





for e in edge[-1]:

    if 0 in edge[e]:

        print('POSSIBLE')

        exit()



print('IMPOSSIBLE')
# 2019/08/05



input=open(0).readline



n,m=list(map(int,input().split()))

edge=[[] for _ in range(n)]

for i in range(m):

    a,b=list(map(int,input().split()))

    a-=1;b-=1

    edge[a].append(b)

    edge[b].append(a)





for e in edge[-1]:

    if 0 in edge[e]:

        print('POSSIBLE')

        exit()



print('IMPOSSIBLE')
# 2019/08/05
n, m = list(map(int, input().split()))
edge = [[] for _ in range(n)]
for i in range(m):
    a, b = list(map(int, input().split()))
    a -= 1
    b -= 1
    edge[a].append(b)
    edge[b].append(a)
for e in edge[-1]:
    if 0 in edge[e]:
        print("POSSIBLE")
        exit()
print("IMPOSSIBLE")

# 2019/08/05
input = open(0).readline
n, m = list(map(int, input().split()))
edge = [[] for _ in range(n)]
for i in range(m):
    a, b = list(map(int, input().split()))
    a -= 1
    b -= 1
    edge[a].append(b)
    edge[b].append(a)
for e in edge[-1]:
    if 0 in edge[e]:
        print("POSSIBLE")
        exit()
print("IMPOSSIBLE")

+input = open(0).readline