If a cell in column contains "x", return the value

Basically I have a large spreadsheet and I want to pick out the values that I flag with an X. Not all of the rows have an x next to it, but the ones that do have an x, I want to return the value next to it. Like so:
Column A Column B Column C
1 x 1
2 3
3 x 6
4
5
6 x

What do I put in Column C to get what I want?