import random
for z in range(3000):
 i=random.randrange(3)
 l,r=I[i]
 yl=random.randrange(l,r+1)
 yu=min(r,yl+random.randrange(0,50))
 Y=tuple(range(yl,yu+1))
 t=random.randrange(p)
 R=set(rng(Y,t,I[i]))
 B={b for b in range(l,r+1) if all(inV((y+b)%p,t) for y in Y)}
 if R!=B:
  print('BAD',z,i,t,yl,yu,R,B)
  break
else:print('OK')