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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. typedef long long iint;
  4.  
  5. int main() {
  6.     iint n;
  7.     cin >> n;
  8.     iint sum = (n * (n-1)) / 2;
  9.     while (n > 1) {
  10.         iint a;
  11.         cin >> a;
  12.         sum -= a;
  13.         n--;
  14.     }
  15.     cout << sum;
  16. }
Success #stdin #stdout 0.01s 5312KB
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stdin
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5
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-1
https://ideone.com/Hyrpyi
language:
C++14 (gcc 8.3)
created:
4 hours ago
visibility:
public

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