main
unknown 2024-01-17 14:08:41 +02:00
commit 9a7ae9c957
1 changed files with 26 additions and 0 deletions

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from collections import defaultdict
# I
N, M = map(int, input().split())
cup = defaultdict(int)
for _ in range(N):
x, s = map(int, input().split())
cup[x] += s
# summa dalās ar M
pairs = 0
for x in cup:
if x >= M - x and cup[x] > 0:
if x == M - x:
pairs += cup[x] // 2
cup[x] %= 2
else:
if M - x in cup:
pairs += min(cup[x], cup[M - x])
cup[x] -= min(cup[x], cup[M - x])
cup[M - x] -= min(cup[x], cup[M - x])
print(pairs)