import sys
import io, os
input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline

n,m = map(int, input().split())
edge = [set() for i in range(n)]
for i in range(m):
    a,b = map(int, input().split())
    edge[a].add(b)
    edge[b].add(a)

ans = 0
buy = set()
for v in reversed(range(n)):
    flag = False
    for u in edge[v]:
        if u > v and u not in buy:
            flag = True
            break
    if flag:
        ans |=(1<<v)
        buy.add(v)
print(format(ans, 'b'))