Two monkeys robbed a part of 26 peach nails first, and robbed half of them as soon as they saw anyone. They refused to accept it and walked from one game to another.

Before Monkey A returned the five monkeys to Monkey B, Monkey A had 2+5×2 = 12 monkeys, (26+ 12)÷2 = 19 monkeys, and Monkey B had 26- 19 monkeys.

Before Monkey A snatched half from Monkey B, Monkey B had 7×2 = 14, and Monkey A had 26-14 =12;

Before Monkey B snatched half from Monkey A, Monkey A had 12×2 = 24, which means Monkey A initially took 24 peaches.