■ The penultimate step is 15-4= 1 1, so others take 1 or two or three, and the last one can always be caught by themselves.

■ penultimate step 1 1-4=7,

■ penultimate step 7-4=3,

■ The first step must take three steps.

Similar topic: When two people play catch game, the rule is: after catching 10 balls, each person can only catch 1 or 2 balls at a time. After catching once, the other person catches it in turn, so whoever catches the last ball of 1 will win, so if the person of 1 starts to catch it, ※ [ 1 ]

Have you summed up the method? I also have two questions:

Two people play catch. Rule: When catching 15 balls, each person can only catch 1 or 3 balls at a time. After catching it once, the other party will catch it in turn. Whoever catches the last 1 ball wins. Will the person who starts to catch/kloc-0 win? If he can win, he must catch () balls first?

Two people play catch. Rule: When catching 15 balls, each person can only catch 1 or 4 balls at a time. After catching it once, another person catches it again, so they take turns catching it. Whoever catches the last 1 ball will win, so will the person who starts to catch 1 win? If he can win, he must catch () balls first?