Let's take Keno for example:
There are C(80,20) = 3,535,316,142,212,174,320 ways the casino can draw 20 numbers range from 1 to 80.
Given that the sum of the 20 numbers($x) drawn is $n, the conditions are as below:
Eg. If $n = 210, which is the minimum sum, 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20 = 210. Therefore, there is only one possible combination for the sum of 20 numbers to be 210.
Input: $n = 210
Output : 1