首先读取一串列标号，这些列标号成对出现，表示输入行的列范围。这串列标号以一个负值结尾，作为结束标志。剩余的输入行被程序读入并打印，然后输入行中被选中范围的字符串被提取出来并打印。注意，每行第1列的列标号为零-First reads a serial label, label these columns appear in pairs, which means input line column range. This serial label with a negative end, as the end marker. The remaining input lines are read into the program and printed, and the input line is selected in the range of character string is extracted and printed. Note that each row and a column label to zero