import sys
sys.setrecursionlimit(10 ** 7)
n = int(input())
cnt = [0 for i in range(2 * 10 ** 5)]
G = [[] for i in range(2 * 10 ** 5)]
s = set()
for _ in range(n):
    h, w = map(int, input().split())
    G[h - 1].append(w - 1)
    G[w - 1].append(h - 1)
    cnt[h - 1] += 1
    cnt[w - 1] -= 1
    s.add(h - 1)
    s.add(w - 1)
vis = [0] * (2 * 10 ** 5)
def dfs(v):
    vis[v] = 1
    for u in G[v]:
        if not vis[u]: dfs(u)
dfs(list(s)[0])
if not all(vis[i] for i in s): exit(print(0))
tmp = sum(abs(cnt[i]) for i in range(2 * 10 ** 5)) 
if tmp == 0: print(n)
elif tmp == 2: print(1)
else: print(0)