N=int(input())
k=1
while k<64:
	a,s,i,k=[1]+[2**j for j in range(k)],2**k,0,k+1
	while s<N:a,s,i=a+[s],s*2-a[i],i+1
	if s==N:break
print([k,[2,-1][N>1]][s>N])