n=int(input())

M=200001
par=[-1]*M
def root(a):
    if par[a]<0:
        return a
    return root(par[a])
def same(a, b):
    return root(a)==root(b)
def merge(a,b):
    if same(a,b):return
    a=root(a)
    b=root(b)
    if par[a]>par[b]:a,b=b,a
    par[a]+=par[b]
    par[b]=a
def sz(a):
    return -par[root(a)]

a=[list(map(lambda x:int(x)-1, input().split())) for i in range(n)]
deg = [0]*M
V=set()
for x,y in a:
    merge(x,y)
    V.add(x)
    V.add(y)
    deg[x]-=1
    deg[y]+=1
if sz(a[0][0]) == len(V):
    st=set()
    for i in range(M):
        st.add(deg[i])
    if len(st) > 2:
        print(1)
    else:print(len(V))
else:
    print(0)