Solution:

1. Use IDA to disassemble the binary

Similar process as before, find the DialogFunc and analyze the disassembled assembly code or C pseudocode.

2. Getting in depth into assembly instruction

.text:004013AE                 add     eax, 45370DF7h
.text:004013B3                 add     esp, 0Ch
.text:004013B6                 xor     eax, 0AAFBBCBEh
.text:004013BB                 add     eax, 0D1507BAh
.text:004013C0                 rol     ecx, 5
.text:004013C3                 xor     eax, 0BA14C823h
.text:004013C8                 cmp     eax, 45BEB206h
.text:004013CD                 jnz     short loc_4013F3 

Here the assembly code perform a series of operations:

1. Add 0x45370DF7
2. XOR 0x0AAFBBCBE
3. Add 0x0D1507BA
4. Xor OxBA14C823
5. Finally it compares the value with 0x45BEB206, if matches then print out correct

3.Reverse the operation

Here is the C implementation code to reverse the operation

#include <stdio.h>

int main() {
    int sum = 0x45BEB206;
    sum ^= 0x0BA14C823;
    sum -= 0x0D1507BA;
    sum ^= 0x0AAFBBCBE;
    sum -= 0x45370DF7;
    printf("%x",sum);
    return 0;
}

After running the code, it will return 1337c0de. This is the correct input string.

Flag: 1337c0de