import sys
sys.setrecursionlimit(1000000000)
n = int(input())
if n==1:
print(1)
quit()
edges = [[] for i in range(n+1)]
par = [-1 for i in range(n+1)]
visited = [False for i in range(n+1)]
for i in range(n-1):
a,b = map(int, input().split())
edges[a].append(b)
edges[b].append(a)
sus = input()
for i in range(1,n+1):
if len(edges[i]) == 1:
root = i
flag = False
def dfs(a):
global flag
for i in edges[a]:
if sus[a-1]==sus[i-1] and sus[i-1]=="1":
flag = True
if not visited[i]:
par[i] = a
visited[i] = True
dfs(i)
visited[root] = True
dfs(root)
dps = [-1 for i in range(n+1)]
used = [0 for i in range(n+1)]
def dp(a):
if dps[a] != -1:
return dps[a]
if sus[a-1]=="0":
sums = 0
for i in edges[a]:
if i == par[a]: continue
sums += dp(i)
dps[a] = sums
return sums
dps[a] = 1
maxi = 0
for i in edges[a]:
if i == par[a]: continue
maxi += dp(i)
if dps[a] <= maxi-1:
used[a] = 1
dps[a] = max(dps[a], maxi-1)
return dps[a]
ans = dp(root)
if used[root]:
ans += 2
elif sus[root-1]=="1":
ans += 1
if flag:
print(max(2,ans))
else:
print(ans)
