将给定的字符串，按照规格压缩，输出压缩后的字符串。压缩规格为：相同字符连续，则压缩为“字符+数字个数”，如”aaaa”压缩为”a4”-Given string, in accordance with specifications compression, the compressed output string. Compression standard is: the same character continuously, then the compression is " the number of characters+ numbers"　such as " aaaa"　compressed " a4"