Python

from collections import defaultdict 
 
n = int(input()) 
values = list(map(int, input().split())) 
 
graph = defaultdict(list) 
for _ in range(n - 1): 
    u, v = map(int, input().split()) 
    u -= 1 
    v -= 1 
    graph[u].append(v) 
    graph[v].append(u) 
 
center_count = 0 
for i in range(n): 
    is_center = True 
    for neighbor in graph[i]: 
        if values[i] == values[neighbor]: 
            is_center = False 
            break 
    if is_center: 
        center_count += 1 
 
print(center_count)