Error(s):

850655390/source.f:1:7:

 PROGRAM.TEST
       1
Error: Invalid form of PROGRAM statement at (1)
850655390/source.f:9:20:

 CHARACTER(LEN=20)::C
                    1
Error: Unexpected data declaration statement at (1)
850655390/source.f:10:2:

 C="MATHEMATICS"
  1
Error: Can't convert CHARACTER(1) to REAL(4) at (1)
850655390/source.f:11:13:

 PRINT*,TRIM (C)
             1
Error: ‘string’ argument of ‘trim’ intrinsic at (1) must be CHARACTER