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# Uses python3
import sys
def explore(adj, v, visited, prev, postv, clock):
visited.append(v)
prev[v] = clock[0]
clock[0] = clock[0] + 1
for n in adj[v]:
if n not in visited:
explore(adj, n, visited, prev, postv, clock)
postv[v] = clock[0]
clock[0] = clock[0] + 1
def dfs(adj, visited, prev, postv, clock):
for v in range(len(adj)):
if v not in visited:
explore(adj, v, visited, prev, postv, clock)
def acyclic(adj):
visited = []
prev = [0 for i in range(len(adj))]
postv = [0 for i in range(len(adj))]
clock = [0]
dfs(adj, visited, prev, postv, clock)
for u in range(len(adj)):
for v in adj[u]:
if postv[u] <= postv[v]:
return 1
return 0
if __name__ == '__main__':
input = sys.stdin.read()
data = list(map(int, input.split()))
n, m = data[0:2]
data = data[2:]
edges = list(zip(data[0:(2 * m):2], data[1:(2 * m):2]))
adj = [[] for _ in range(n)]
for (a, b) in edges:
adj[a - 1].append(b - 1)
print(acyclic(adj))
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