A line  of Russian soldiers stands in front of a huge
rectangular hole in the ground.
Sergant commands:- "Private Ivanov!"
                 -  "Yes, sir."
                 -  "Stand like this:"

                          O
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                  -"Jump!!"

The soldier jumps  into  the  hole.
The sergant  commands again:
                     -  "Private  Pyetrov!!"
                     -  "Yes, sir!"
                     -  "Stand like this:"

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                       |  O
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                          \-\
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                       -" Yes, sir!"
                       -" Jump!"

  The soldier jumps and falls into the  hole.
  The sergant commands  again:
                        -" Private Sidorov!!"
                        -" Yes, sir!"
                        _" Stand  like  this:"

                             O
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                          -"  Yes,  sir!"
     At  this point a car with a colonel arrives to  that 
     place.  Colonel, very angry, comes up to the sergant 
     and tells him: "Comrad sergant, how many times do
     I have to tell  you: STOP PLAYING TETRIS WITH  THE 
     SOLDIERS!!!!!!!!!"