N=int(input())
k=s=1
while k<64 and s!=N:
	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
print([[k,2][N<2],-1][s>N])