View Compilation Error

0_0_37399574_3723\Main.java:1: 错误: 需要class, interface或enum
using System;
^
0_0_37399574_3723\Main.java:3: 错误: 需要class, interface或enum
namespace a1
^
0_0_37399574_3723\Main.java:7: 错误: 非法的类型开始
		public const int M = 50;
		       ^
0_0_37399574_3723\Main.java:7: 错误: 需要';'
		public const int M = 50;
		            ^
0_0_37399574_3723\Main.java:7: 错误: 需要<标识符>
		public const int M = 50;
		                  ^
0_0_37399574_3723\Main.java:75: 错误: 需要class, interface或enum
}
^
6 个错误