View Compilation Error

0_0_36741233_1064.cpp:1:1: error: expected unqualified-id before 'public'
 public static BigInteger sum(BigInteger a,BigInteger b) {
 ^
0_0_36741233_1064.cpp:4:5: error: expected unqualified-id before 'public'
     public static void main(String[] args) {
     ^