disassembly c program with gdb get error

When I disassemble c program with gdb, I get error. I googled it but no result found that I want. Can someone help me?

my document first.asm is:

global main     
main:
   mov eax, 1
   mov ebx, 2
   add eax, ebx
   ret                                                                                                                                         






root@kali-linux:~/my-document/test# gdb ./first 
GNU gdb (Debian 7.12-6) 7.12.0.20161007-git
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
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copying"
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For help, type "help".
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Reading symbols from ./first...(no debugging symbols found)...done.
(gdb) set disassembly-flavor intel
(gdb) disas main
Dump of assembler code for function main:
   0x000004f0 <+0>: mov    eax,0x1
   0x000004f5 <+5>: mov    ebx,0x2
   0x000004fa <+10>:    add    eax,ebx
   0x000004fc <+12>:    ret    
   0x000004fd <+13>:    xchg   ax,ax
   0x000004ff <+15>:    nop
End of assembler dump.
(gdb) break *0x000004fa
Breakpoint 1 at 0x4fa
(gdb) run
Starting program: /root/my-document/test/first 
Warning:
Cannot insert breakpoint 1.
Cannot access memory at address 0x4fa

(gdb) 

Here is error: enter image description here

I restart disassemble c program with gdb,and I do it with b 4 instead of break*0x000004fa and run the code ,it still can not work!

I think the correct output should be:

(gdb) run
Starting program: /root/my-document/test/first
Breakpoint 1, 0x000004fa in main()
(gdb)