problem 2.1.c

I face some difficulty with problem 2.1.c. Let A be an algorithm . The first price p1 set by A can be seen as a constant (it is independent of the players bids), so let's say that p1=5. Consider players with v_1=...=v_{n-1}=6 and v_n = 10^9. With probability (n-1)/n, the first bid is 6, and since 6>5 the auction is completed with welfare 6. What am I missing?