In a cooking competition, chefs were required to make one hot dish and one cold dish, and the results were rated as top grade, middle grade and low grade  If every result of the chef is not lower than that of the chef B, and at least one of the results is higher than that of the chef B, it is said that the chef A is more skilled than the chef B
There are several chefs, none of them is more skilled than the other, and no two of them have the same results in hot dishes and the same in cold dishes
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