27 lines
619 B
Python
27 lines
619 B
Python
from sys import stdin
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n=int(stdin.readline().rstrip())
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stack=[]
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for _ in range(n):
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s=stdin.readline().rstrip().split()
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if len(s)==1:
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if s[0]=='pop':
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if len(stack)==0:
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print(-1)
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else:
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print(stack.pop())
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elif s[0]=='top':
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if len(stack)==0:
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print(-1)
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else:
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print(stack[-1])
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elif s[0]=='size':
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print(len(stack))
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else:
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if len(stack)==0:
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print(1)
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else:
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print(0)
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else:
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stack.append(int(s[1])) |