a,b,c=map(int,input().split())

def eval(i: int) ->int:
  res = (10 * (c-i) + i) - (10 * b + a)
  return res

list=[0]*(c+1)

for i in range(c+1):
  list[i]=eval(i)

eval=list.pop(0)
while(eval > 0):
  eval=list.pop(0)

if eval > 0:
  print("Impossible")
else:
  print(abs(eval))