Change the ball

Garfield has three piles of balls, each pile has unique color of following: yellow, blue, and red. Now we also know Garfield has Y yellow balls, B blue balls, and R red balls. But Garfield just wants to change all the balls to one color. When he puts two balls of different color togather, the balls then change their colors automatically into the rest color. For instance, when Garfield puts a red one and a yellow one togather, the two balls immediately owns blue color, the same to other situations. But the rule doesn’t work when the two balls have the same color.
  Garfield is not able to estimate the minimal steps to achieve the aim. Can you tell him?

For each line, there are three intergers Y, B, R(1<=Y,B,R<=1000),indicate the number refered above.

For each case, tell Garfield the minimal steps to complete the assignment. If not, output the symbol “):”.

1 2 3
1 2 2

):
2

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