19 lines
264 B
Python
19 lines
264 B
Python
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average = int(input(""))
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assignments = int(input(""))
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"""
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(average*2+x)/3=80
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average*2+x=240
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x=240-average*2
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"""
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required = 80*(assignments+1) - average*assignments
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if required > 100:
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print("-1")
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elif required < 0:
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print("0")
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else:
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print(required)
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