Decompile with Ghidra:

```
fgets(local_1014,0xfff,_stdin);
for (local_1090 = local_1014; *local_1090 != '\0'; local_1090 = local_1090 + 1) {
*local_1090 = *local_1090 + '\a';
}
*local_1090 = '\0';
iVar1 = memcmp(&DAT_00012039,local_1014,0xe);
```

Seems like this section of main is adding '\a' to every byte of out input, and then checking if it equals some variable.
Double clicking on that variable locates its byte values. So, we can just reverse this with a simple python program!

```
b = [0x4D, 0x79, 0x7C, 0x70, 0x7B, 0x80, 0x47, 0x52, 0x59, 0x5C, 0x4C, 0x4E, 0x4C, 0x59]

for i in b:
print(chr(i - ord('\a')), end='')
```

Our input is thus

Fruity@KRUEGER

And we get

flag{I_am_REDDY_for_FREDDY!!!}