We're given this long script:
```(defun checkFlag (input)    (if (not (= (length input) 34))        nil        (if (not (string= (subseq input 0 6) "UDCTF{"))            nil            (if (not (= (char-code (char input 6)) 104))                nil                (if (not (= (+ (char-code (char input 9)) 15) (- (char-code (char input 8)) (char-code (char input 7)))))                    nil                    (if (not (= (* (char-code (char input 7)) (char-code (char input 9))) 2652))                        nil                        (if (not (= (- (char-code (char input 7)) (char-code (char input 9))) 1))                            nil                            (if (not (string= (char input 10) (char input 14) ) )                                nil                                (if (not (string= (char input 14) (char input 21) ) )                                    nil                                    (if (not (string= (char input 10) (char input 25) ) )                                        nil                                        (if (not (string= (char input 21) (char input 27) ) )                                            nil                                            (if (not (= (ceiling (char-code (char input 10)) 2) (char-code (char input 12)) ) )                                                nil                                                (if (not (=  952 (- (expt (char-code (char input 11)) 2) (expt (char-code (char input 13)) 2)) ) )                                                    nil                                                    (if (not (string= (subseq input 14 21) (reverse "sy4wla_")))                                                        nil                                                        (if (not (string= (subseq input 22 24) (subseq input 6 8)))                                                            nil                                                            (if (not (= (mod (char-code (char input 24)) 97)  3))                                                                nil                                                                (if (not (string= (subseq input 14 16) (reverse (subseq input 26 28))))                                                                    nil                                                                    (if (not (= (complex (char-code (char input 28)) (char-code (char input 29)))  (conjugate (complex 76 -49))))                                                                        nil                                                                        (if (not (= (lcm (char-code (char input 30)) (char-code (char input 31))) 6640))                                                                            nil                                                                            (if (not (> (char-code (char input 30)) (char-code (char input 31)) ) )                                                                                nil                                                                                (if (not (= (char-code (char input 32)) (- (+ (char-code (char input 31)) (char-code (char input 30))) (char-code (char input 24)))))                                                                                    nil                                                                                    (if (not (= (char-code (char input 33)) 125))                                                                                        nil                                                                                        t))))))))))))))))))))))
(print (checkFlag "FLAGHERE")```
I had absolutely no idea what language this was, so I decided to do it all by hand, line by line!  
```length=34[0-5]=UDCTF{[6]=h[7-9]=4v3    15 + [9] = [8] - [7]    [7][9] = 2652 --> factor --> 52, 51 --> "4", "3"    [7] - [9] = 1 --> [7] = "4", [9] = "3"    [8] = 118 = 'v'[10]=[14]=[21]=[25]=[27]=_[12] = ceiling([10] / 2) (guess) = 0[11]^2 - [13]^2 = 952 11and13.py (see below)    [11]=121, [13]=117[14-20]=_alw4ys[22-23]=[6-7]=h4[24] % 97 = 3 --> [24]=100reverse([26-27]) = [14-15] --> [26-27]=a_[28]=76, [29]=49lcm([30],[31]) = 6640 --> factor --> 2^4 * 5 * 83 --> 80, 83[30] > [31] --> [30-31]=83 80=SP[32] = [31] + [30] - [24] = 80 + 83 - 100 = 63 = ?[33] = 125```
Note that for [11] and [13], I used a python script to figure them out:
```import gmpy2
for i in range(200):    a = gmpy2.iroot(952 + i*i, 2)    if a[1]:        print(a[0], i)```
And for [12], I guessed that, since we were using the ceiling function, and [10] was an underscore, or 95 in ASCII code, it was probably just getting divided by the 2 in the code.  
	UDCTF{h4v3_y0u_alw4ys_h4d_a_L1SP?}