/in/foo.c:1:1: error: unknown type name 'def'
 def FindMaxNeg(arr):
 ^~~
/in/foo.c: In function 'FindMaxNeg':
/in/foo.c:1:20: error: expected declaration specifiers before ':' token
 def FindMaxNeg(arr):
                    ^
/in/foo.c:1:5: warning: type of 'arr' defaults to 'int' [-Wimplicit-int]
 def FindMaxNeg(arr):
     ^~~~~~~~~~
/in/foo.c:22:5: warning: control reaches end of non-void function [-Wreturn-type]
     main()
     ^~~~