Find a RedSpica

from collections import defaultdict

​

class UnionFind():

    def __init__(self, n):

        self.n = n

        self.parents = [-1] * n

​

    def find(self, x):

        if self.parents[x] < 0:

            return x

        else:

            self.parents[x] = self.find(self.parents[x])

            return self.parents[x]

​

    def union(self, x, y):

        x = self.find(x)

        y = self.find(y)

​

        if x == y:

            return

​

        if self.parents[x] > self.parents[y]:

            x, y = y, x

​

        self.parents[x] += self.parents[y]

        self.parents[y] = x

​

    def size(self, x):

        return -self.parents[self.find(x)]

​

    def same(self, x, y):

        return self.find(x) == self.find(y)

​

    def members(self, x):

        root = self.find(x)

        return [i for i in range(self.n) if self.find(i) == root]

​

    def roots(self):

        return [i for i, x in enumerate(self.parents) if x < 0]

​

    def group_count(self):

        return len(self.roots())

​

    def all_group_members(self):

        group_members = defaultdict(list)

        for member in range(self.n):

            group_members[self.find(member)].append(member)

        return group_members

​

    def __str__(self):

        return '\n'.join(f'{r}: {m}' for r, m in self.all_group_members().items())

​

N=int(input())

b=list(map(int,input().split()))

c=list(input().split())

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M=int(input())

uf=UnionFind(N+1)

​

for i in range(M):

    x,y=map(int,input().split())

    uf.union(x,y)

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D=dict()

for x in range(1,N+1):

    p=uf.find(x)

    D[p]=max(D.get(p,0),b[x-1])

​

ans=0

for x in range(1,N+1):

    p=uf.find(x)

    if D[p]==b[x-1] and c[x-1]=='R':

        ans+=1

​

print(ans)