By examining the code we can see there are many variables that probably contain the flag characters:
```
int *piVar1;
undefined4 extraout_EDX;
undefined4 extraout_EDX_00;
undefined4 extraout_EDX_01;
undefined4 extraout_EDX_02;
undefined4 extraout_EDX_03;
```

Each character of the flag is printed by dividing a number by 1337

```
operator>>((basic_istream<char,struct_std::char_traits<char>_> *)cin_exref,&local_10);
piVar1 = FUN_00401170((int *)cout_exref,CONCAT31((int3)((uint)extraout_EDX >> 8),0x53));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_00 >> 8),0x42));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_01 >> 8),0x43));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_02 >> 8),0x54));
FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_03 >> 8),0x46));
piVar1 = FUN_00401170((int *)cout_exref,CONCAT31((int3)((uint)extraout_EDX_04 >> 8),0x7b));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_05 >> 8),0x53));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_06 >> 8),0x65));
FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_07 >> 8),0x72));
piVar1 = FUN_00401170((int *)cout_exref,CONCAT31((int3)((uint)extraout_EDX_08 >> 8),0x69));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_09 >> 8),0x61));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_10 >> 8),0x6c));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_11 >> 8),0x5f));
FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_12 >> 8),0x6e));
piVar1 = FUN_00401170((int *)cout_exref,CONCAT31((int3)((uint)extraout_EDX_13 >> 8),0x75));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_14 >> 8),0x6d));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_15 >> 8),0x62));
FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_16 >> 8),0x33));
piVar1 = FUN_00401170((int *)cout_exref,CONCAT31((int3)((uint)extraout_EDX_17 >> 8),0x72));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_18 >> 8),0x5f));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_19 >> 8),0x61));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_20 >> 8),99));
FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_21 >> 8),99));
piVar1 = FUN_00401170((int *)cout_exref,CONCAT31((int3)((uint)extraout_EDX_22 >> 8),0x65));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_23 >> 8),0x70));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_24 >> 8),0x74));
piVar1 = FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_25 >> 8),0x33));
FUN_00401170(piVar1,CONCAT31((int3)((uint)extraout_EDX_26 >> 8),100));
FUN_00401170((int *)cout_exref,CONCAT31((int3)((uint)extraout_EDX_27 >> 8),0x7d));
FUN_0040168a();
```

flag:
> SBCTF{Serial_numb3r_accept3d}