Calculate 3 period cumulative PD for Rating A. What is the 3 year survival rate for Rating A? please show the calculation steps.

Rating at beginning of period A B C Default Rating at end of period. A B C Default 0.95 0.05 0.00 0.00 0.03 0.90 0.90 0.05 0.02 0.01 0.10 0.75 0.14 0.00 0.00 0.00 0.00 1.00