#yuki_479

n,m=map(int,raw_input().split())
g=[]
for i in xrange(m):
 a,b=map(int,raw_input().split())
 g.append([a,b])
g.sort()
g.reverse()

s=set()
for i in xrange(m):
 if g[i][1] in s:
  continue
 s.add(g[i][0])

res=0
for i in s:
 res+=1<<i
print bin(res)[2:]