Help with an IF OR Function

[holykimura]

Hi I have two columns of data that contain values from 1 to 9 as well as the value "U". In a third column, i'm trying to determine whether a cell is equal to or above 7 in the either of the columns and if it is enter an "e" and if not " enter a "-". I am using the formula below however if the it is still it is not working in that when a "U" is present it still enters an "e" instead of a "-". I have attached an example and a fourth column of what it should be showing. If someone could help i would really appreciate it.

=IF(OR(A2>=7,B2>=7),"e",IF(OR(A2="U",B2="U"),"-","-"))