OLL 12 algorithm: Upstairs
OLL (orient the last layer). Group: Small lightning bolt shapes.
OLL 12, Upstairs: yellow stickers on the top face: back-left corner, back edge, centre, right edge. Yellow stickers on the sides: back face, right, right face, front, front face, left, front face, centre, left face, middle.
The diagram shows the cube from above with the front at the bottom and yellow on top.
Algorithm
M' R' U' R U' R' U2 R U' M
10 moves.
Other algorithms
r R2 U' R U' R' U2 R U' r' RF R U R' U' F' U F R U R' U' F'y' M' R' U' R U' R' U2 R U' M
Source: www.speedcubedb.com