Birthday problem(Desperate -.-)

The birthday problem is the probability of any 2 people out of n people having the same birthday. Did you know that out of only 57 people there is a 99% chance that 2 people have the same birthday? This is because every person must have a different birthday with all other people. The probability of 2 people having the same birthday is 1 x (1-1/365) x (1 - 2/365) x ... x ( 1- (n-1)/365). When you substitute n with 57, you find that its probability is 99%! This is hard to believe if you do not know the logic but it is true!