In bowling, you get two turns per frame, and you want to knock down all 10 pins in a frame. If you knock them down on the first turn, it is a strike, and you will not take the second turn in that frame. If you knock them down in 2 turns, it is a spare.

If you don't knock them all down with 2 turns, your score for that frame is the number you knocked down in the 2 turns.

If you bowl a spare in a frame, the score for the frame includes the number of pins you knock down in the first ball of the next frame.

If you bowl a strike in a frame, your score for the frame includes the pins you knock down in both turns of the next frame.

Given the number of pins knocked down in 4 turns (2 frames), calculate the score for the first frame.

a - the number of pins knocked down in the first turn
b - the number of pins knocked down in the second turn (will be 0 if a is a strike)

c - the number of pins knocked down in the third turn
d - the number of pins knocked down in the fourth turn