SUM column C unless value in col A matches col B

Question

I'm trying get a SUM of values in column C only if value in cell A doesn't match any values in column B:

    |   A    |   B   |  C  |
    |--------|-------|-----|
  1 |  Tom   |       | 1   |
  2 |  Mary  |       | 2   |
  3 |  Kevin | Mary  | 4   |
  4 |  Susan | Test  | 8   |
  5 |  Bob   | Eve   | 16  |
  6 |  Eve   | Blah  | 32  |
  7 |  Kat   |       | 64  |

In this example the result would be 93, because Mary and Eve present in column B and ignored

Answer 1

You can use the following, entered as an array formula with CTRL+SHIFT+ENTER:

=SUM(IF(COUNTIF(B1:B7,A1:A7)=0,C1:C7))

_{(Thanks to @JNevill)}

Answer 2

Try this formula:

=SUM(SUMIF(A1:A7,B1:B7,C1:C7))

Type Ctrl+Shift+Enter