We need to acess the negative indices, as they contain the flag.

Since numpy works mod 2^32, we can try and access 2^32-7.

Thus, we need x such that x^2==2^32-7

We can finish this using lifting on sucessive powers of 2, as demostrated by gen().

If we have a solution x with modulo mod, we can try x or x+(mod//2), and one of them will work, because (x+mod//2)^2=x^2+mod modulo (2*mod)

Thus, we get our square root and using it gives the flag.

```
from pwn import *
import numpy as np

def gen(x):
if x%2==0:
assert(x%4==0)
return 2*gen(x//4)
assert(x%8==1)
sqr=1
mod=8
while mod<pow(2,32):
#print(sqr,x,mod)
assert(pow(sqr,2,mod)==x%mod)
A=sqr
B=sqr+mod//2
mod*=2
if (B*B)%mod==x%mod:
sqr=B
else:
sqr=A
assert(pow(sqr,2,pow(2,32))==x)
return sqr

def test(y):
io=remote('52.59.124.14',5016)
# io=process(['python3','chall.py'])
io.sendlineafter(b"participate?",b"1")
g=gen(y)
power = np.zeros(1, dtype = np.int32)
power[0]=g
print(power**2,y)
io.sendlineafter(b"right now?",str(g).encode())
io.sendlineafter(b"to do?",b"1")
io.sendlineafter(b"to do?",b"2")
out=io.recvall()
if b"You got an inspiration" in out:
return True
return False

# lo=1
# hi=10000
# while hi-lo>1:
# mid=(hi+lo)//2
# print(lo,hi)
# if test(8*mid+1):
# lo=mid
# else:
# hi=mid

test(pow(2,32)-7)

```