View Compilation Error

0_0_5578246_24937\Main.java:7: cannot find symbol
symbol  : class Scanner
location: class Main
			Scanner cin= new Scanner(System.in);
			^
0_0_5578246_24937\Main.java:7: cannot find symbol
symbol  : class Scanner
location: class Main
			Scanner cin= new Scanner(System.in);
			                 ^
0_0_5578246_24937\Main.java:8: cannot find symbol
symbol  : class BigInteger
location: class Main
			BigInteger a,b;
			^
3 errors