public static void main(String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); String str; while ((str = br.readLine()) != null) { String[] input = str.split(" "); int count = 0;// 字母的数量 int checkedCount = 0;// 选中的字母数量 int copyCount = 0;// 已复制的字母数量 for (String s : input) { int order = Integer.parseInt(s); // 用数字 12345代表 a,ctrl-c,ctrl-x,ctrl-v,ctrl-a五个键的输入 switch (order) { case 1: count++; break; case 2: copyCount = checkedCount; break; case 3: copyCount = checkedCount; count -= checkedCount; checkedCount = 0; break; case 4: if (copyCount != 0){ count -= checkedCount; checkedCount = 0; count += copyCount; } break; case 5: checkedCount = count; break; } } System.out.println(count); } }