from __future__ import print_function
# n - no of nodes, m - no of edges
n, m = list(map(int,raw_input().split()))

g = [[] for i in range(n)] #graph
r = [[] for i in range(n)] #reversed graph
# input graph data (edges)
for i in range(m):
    u, v = list(map(int,raw_input().split()))
    g[u].append(v)
    r[v].append(u)

stack = []
visit = [False]*n
scc = []
component = []

def dfs(u):
    global g, r, scc, component, visit, stack
    if visit[u]: return
    visit[u] = True
    for v in g[u]:
        dfs(v)
    stack.append(u)

def dfs2(u):
    global g, r, scc, component, visit, stack
    if visit[u]: return
    visit[u] = True
    component.append(u)
    for v in r[u]:
        dfs2(v)

def kosaraju():
    global g, r, scc, component, visit, stack
    for i in range(n):
        dfs(i)
    visit = [False]*n
    for i in stack[::-1]:
        if visit[i]: continue
        component = []
        dfs2(i)
        scc.append(component)
    return scc

print(kosaraju())