TIME: 80


SCC: 7
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Global Ranking Function: nat(-1*A+20)

  2_loop(A) :- 2_loop(B) [1*A+ -1*B= -1,-1*A>= -11]
  2_loop(A) :- 2_loop(B) [1*A+ -1*B= -1,1*B>=13,-1*B>= -20]
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