Find out the missing number in the diagram
Options are
$(A)$ 60
$(B)$ 62
$(C)$ 64
$(D)$ 66
I've been thinking about problem all morning to no avail.
Can't seem to figure out the connection here. Help please!
This problem appeared in a national level civil services exam in India.
"Hint":
$$30=2(7+9)+(-1)^7+(-1)^9+(-1)^5+(-1)^4$$ and $$50=2(17+8)+(-1)^{17}+(-1)^8+(-1)^3+(-1)^6$$
(I use scare quotes around "Hint" here to mean that this is one of many patterns one can attribute to the problem. Note, the powers of $-1$ just means you add $1$ for each even number and subtract $1$ for each odd number.)