42 lines
1002 B
Python
42 lines
1002 B
Python
from sys import stdin
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from collections import deque
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n=int(stdin.readline().rstrip())
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dq=deque()
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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_front':
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if len(dq)==0:
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print(-1)
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else:
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print(dq.popleft())
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elif s[0]=='pop_back':
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if len(dq)==0:
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print(-1)
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else:
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print(dq.pop())
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elif s[0]=='front':
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if len(dq)==0:
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print(-1)
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else:
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print(dq[0])
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elif s[0]=='back':
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if len(dq)==0:
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print(-1)
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else:
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print(dq[-1])
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elif s[0]=='size':
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print(len(dq))
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else:
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if len(dq)==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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if s[0]=='push_front':
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dq.appendleft(int(s[1]))
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else:
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dq.append(int(s[1]))
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