You are located in a room with n doors. If you open the i-th door, in xi hours you will be either get to a safe place or you will return to the same room again. What is the expected time P (in hours) until you can move to the safe place?
The first line is the number of test cases. The first line of each test case contains the value of n(0<n<100). Each of the next n lines contains two numbers xi(0<∣xi∣<25) and pi(0≤pi≤1)
if xi is positive, it indicates the time in which you will get to a safe place;
if xi is negative, then ∣xi∣ indicates the time in which you will return to the room;
The value of pi is the probability to open the i-th door. The sum of all pi equals 1.
For each test case, first print the serial number of the case, a colon, a space and then print “God! Save me” (without the quotes) if you can't expect to be in the safe place, otherwise print the value of P with 6 digits after the decimal point.