1999-2000 ACM Northeastern European Regional Programming Contest
Problem Z
"Sum"
| Input file | SUM.IN
|
| Output file | SUM.OUT
|
| Time limit | 15 seconds per test
|
Your task is to find the sum of all integer numbers
lying between 1 and N inclusive.
Input
The input file consists of a single integer N that is
not greater than 10000 by it's absolute value.
Output
Write to the output file a single integer number that is the sum of all
integer numbers lying between 1 and N inclusive.
Sample input
-3
Output for the sample input
-5