Algorithm
A. Calculating Function
time limit per test
1 secondmemory limit per test
256 megabytesProblem link- https://codeforces.com/problemset/problem/486/A
input
standard inputoutput
standard outputFor a positive integer n let's define a function f:
f(n) = - 1 + 2 - 3 + .. + ( - 1)nn
Your task is to calculate f(n) for a given integer n.
Input
The single line contains the positive integer n (1 ≤ n ≤ 1015).
Output
Print f(n) in a single line.
Examples
input
Copy
4
output
Copy
2
input
Copy
5
output
Copy
-3
Note
f(4) = - 1 + 2 - 3 + 4 = 2
f(5) = - 1 + 2 - 3 + 4 - 5 = - 3
Code Examples
#1 Code Example with C++ Programming
Code -
C++ Programming
#include<iostream>
using namespace std;
int main(){
long long n;
cin>>n;
long long evn = n/2;
long long oddn = n%2 == 0 ? n/2 : (n/2 + 1);
long long sumevn = evn * (evn + 1);
long long sumoddn = oddn * oddn;
long long sum = sumevn - sumoddn;
cout<<sum;
return 0;
}Input
4
Output
2
Demonstration
Codeforcess Solution 486-A A. Calculating Function ,C++, Java, Js and Python ,486-A,Codeforcess Solution