Ordering the third column in excel according to first column (and fill blanks)

I have three columns, two first columns have identical values, the third one has some values missing (below nr. 2 & 4 are missing).

So how can I "order" these:

A B C

1 1 1

2 2 3

3 3 5

4 4

5 5

To become:

A B C

1 1 1

2 2 0

3 3 3

4 4 0

5 5 5

As you can see, the values that are missing are being (i.e. should be) filled with zero. The numbers above are unique (i.e. I can't have two 4's in the same column). So how can I get the same values from Column C to be right next to column B (and then I can fill the empty fields with zero).