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