if p and q are positive integers each greater than 1 , and 17 ( p + 1 ) = 21 ( q + 1 ) , what is the least possible value of p + q ?
n0 = 1.0
n1 = 17.0
n2 = 1.0
n3 = 21.0
n4 = 1.0
t0 = n1 + n3
answer = t0 - 2.0
print(answer)