Problem A - Cops and impostors
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There is a criminal group in town which has members who pose as
policemen. Law enforcement officials are trying to nab the people
involved. Fortunately, there is a bar in town where cops go and so do
the impostors. So the real cops work out a scheme to detect impostors.
They agree that they would coordinate their visits to the bar such that
when there is an odd number of cops, their id (badge) numbers would add
up to an odd number, and when there is an even number of cops the sum of
their id's would be even.

A surveillance camera is set up at the entrance of the bar and connected
to a computer which records entry and exit of cops and their id numbers.
This data is stored in a computer. Your job is to detect whether this
condition is violated, so that the surveillance tapes can be analyzed
and criminals apprehended.
 
Input
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The input consists of several cases. Each case starts with an integer n
that indicates the number of lines in the log for the case. The
following n lines are of the form "<id> enter" where <id> is an id
number. These numbers are positive integers and can be as large as
1,000,000,000. The number n is no more than 1000. The last case is 0 and
has no lines following it. This signifies the end of input and should
not be processed. 

Output
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For each case except the terminating one (the line with 0), output a
single line that says "No impostors detected" or "Impostor(s) detected".

Sample input
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3
1001 enter
2001 enter
3000 enter
0

Output for Sample Input
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Impostor(s) detected