s1 and s2 alphabetically.canS1BreakS2 and canS2BreakS1, to true.s1 is less than the corresponding character in s2, set canS1BreakS2 to false.s2 is less than the corresponding character in s1, set canS2BreakS1 to false.canS1BreakS2 or canS2BreakS1 is true, return true.false.