YES(?,O(n^1))
* Step 1: AddSinks WORST_CASE(?,O(n^1))
    + Considered Problem:
        Rules:
          0. f1(A) -> f1(-1000 + A) [A >= 1001] (?,1)
          1. f0(A) -> f1(A)         True        (1,1)
        Signature:
          {(f0,1);(f1,1)}
        Flow Graph:
          [0->{0},1->{0}]
        
    + Applied Processor:
        AddSinks
    + Details:
        ()
* Step 2: LooptreeTransformer WORST_CASE(?,O(n^1))
    + Considered Problem:
        Rules:
          0. f1(A) -> f1(-1000 + A) [A >= 1001] (?,1)
          1. f0(A) -> f1(A)         True        (1,1)
          2. f1(A) -> exitus616(A)  True        (?,1)
        Signature:
          {(exitus616,1);(f0,1);(f1,1)}
        Flow Graph:
          [0->{0,2},1->{0,2},2->{}]
        
    + Applied Processor:
        LooptreeTransformer
    + Details:
        We construct a looptree:
          P: [0,1,2]
          |
          `- p:[0] c: [0]
* Step 3: SizeAbstraction WORST_CASE(?,O(n^1))
    + Considered Problem:
        (Rules:
          0. f1(A) -> f1(-1000 + A) [A >= 1001] (?,1)
          1. f0(A) -> f1(A)         True        (1,1)
          2. f1(A) -> exitus616(A)  True        (?,1)
        Signature:
          {(exitus616,1);(f0,1);(f1,1)}
        Flow Graph:
          [0->{0,2},1->{0,2},2->{}]
        
        ,We construct a looptree:
          P: [0,1,2]
          |
          `- p:[0] c: [0])
    + Applied Processor:
        SizeAbstraction UseCFG Minimize
    + Details:
        ()
* Step 4: FlowAbstraction WORST_CASE(?,O(n^1))
    + Considered Problem:
        Program:
          Domain: [A,0.0]
           f1  ~>  f1          [A <= A]
           f0  ~>  f1          [A <= A]
           f1  ~>  exitus616   [A <= A]
          + Loop: [0.0 <= 1000*K + A]
               f1  ~>  f1   [A <= A]
    + Applied Processor:
        FlowAbstraction
    + Details:
        ()
* Step 5: LareProcessor WORST_CASE(?,O(n^1))
    + Considered Problem:
        Program:
          Domain: [tick,huge,K,A,0.0]
           f1  ~>  f1          []
           f0  ~>  f1          []
           f1  ~>  exitus616   []
          + Loop: [A ~+> 0.0,K ~*> 0.0]
               f1  ~>  f1   []
    + Applied Processor:
        LareProcessor
    + Details:
         f0  ~>  exitus616   [A ~+> 0.0,A ~+> tick,tick ~+> tick,K ~*> 0.0,K ~*> tick]
        + <f1  ~>  f1>  [A ~+> 0.0,A ~+> tick,tick ~+> tick,K ~*> 0.0,K ~*> tick]

YES(?,O(n^1))