Not wanting to because you're too lazy on account of the heat and lack of interest (I don't want to know all that badly) does not equal not being able to make the calculation. You add up the total number of votes, the total number of unique voters, and take the difference between two times number of voters and the actual number of votes cast. But that's a lot more boring to do than it is to explain.
Another way is to go over the entire list of voters noting each time they appear for each candidate and then listing the people with only one occurrence.