$16$
25. There are 100 cards, each with a number from $1 \sim 100$. After Miaomiao takes some cards, Mickey finds that although the remaining cards are less than 100, they can still form any number from 1 to 100, because some cards can be flipped, for example, 1 flipped is 1, 6 flipped is 9, 25 flipped is 52. How many cards did Miaomiao take at most? (Note: 0 cannot be the leading digit) The numbers on the cards are written as follows:



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