In your output file, there should be a line at the beginning saying "crystal axes: cart. coord. in units of alat)" like the following:
crystal axes: (cart. coord. in units of alat)
a(1) = ( 1.000000 0.000000 0.000000 )
a(2) = ( 0.000000 1.000000 0.000000 )
a(3) = ( 0.000000 0.000000 1.000000 )
Check these three lines to obtain the lattice vector. For example, if it is like the above, then what you have done is correct. If it is, let's say 0.5 instead of 1, then you have to divide what you have got with 0.5.
You don't have to consider other numbers to get the lattice parameter since for ibrav=1, the lattice vector components are 0. But it is always a good practice to check the output file to make sure your lattice vectors are as you would expect. Also note that the unit is in Bohr.