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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main(){
  5.     int N;
  6.     cin >> N;
  7.  
  8.      if (N < 2 || N >= 200000) {
  9.    return 0;
  10. }
  11.  
  12.     int arr[N];
  13.     for (int i = 0; i < N-1; i++) { 
  14.         cin >> arr[i];
  15.     }
  16.  
  17.     sort(arr, arr+N-1);
  18.  
  19.     for (int i = 0; i < N-1; i++) { 
  20.         if (arr[i] != i+1) {
  21.             cout << i+1 << endl;
  22.             break;
  23.         }
  24.     }
  25. }
  26.  
Success #stdin #stdout 0.01s 5280KB
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https://ideone.com/4S3Grt
language:
C++ (gcc 8.3)
created:
223 days ago
visibility:
public

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