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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int main() {
  5.     int n;
  6.     cin >> n;
  7.  
  8.     double c = 0;
  9.     int a = 1;
  10.  
  11.     for (int k = 2; k <= n; k++, a = -a) {
  12.         c = c + a * 1.0 / (k * k - 1);
  13.     }
  14.  
  15.     cout <<c << endl;
  16.  
  17.     return 0;
  18. }
Success #stdin #stdout 0.01s 5320KB
comments (?)
stdin 
5
stdout 
0.233333
https://ideone.com/fsKSVH
language:
C++ (gcc 8.3)
created:
15 days ago
visibility:
public

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