from functools import lru_cache
import sys
import io
import os
MOD = 998244353
sys.setrecursionlimit(5000)
def main():
for _ in range(read_int()):
n, m = read_int_tuple()
a = read_int_list()
rg = [[] for _ in range(n)]
ss = set(range(n))
for _ in range(m):
u, v = read_int_tuple()
rg[v - 1].append(u - 1)
ss.discard(u - 1)
@lru_cache(None)
def dfs(u):
r = a[u]
s, e = 1, a[u]
book = []
for v in rg[u]:
last, end = dfs(v)
if last == 0:
continue
book.append((end - last + 2, end + 1))
book.sort()
for vs, ve in book:
if vs > e:
s, e = ve - (ve - vs + 1 + e - s + 1) + 1, ve
else:
e += ve - vs + 1
return e - s + 1, e
print(dfs(ss.pop())[1] % MOD)
def input(): return sys.stdin.readline().rstrip('\r\n')
def read_int_list():
return list(map(int, input().split()))
def read_int_tuple():
return tuple(map(int, input().split()))
def read_int():
return int(input())
if __name__ == "__main__":
main()
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