real  a(3),b(3)
open(10,file="test10.in")
read (10,*) a,b
print *,a,b

anorm=0.
bnorm=0.
scal=0.
do i=1,3
anorm=anorm+a(i)**2
bnorm=bnorm+b(i)**2
scal=scal+a(i)*b(i)
enddo
angle=acos(scal/sqrt(anorm*bnorm))
print *, angle*180/3.1415926536
stop
end