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  1. #include <bits/stdc++.h>
  2. #define int long long 
  3. using namespace std;
  4. // Hàm tà đạo :)
  5. bool isPrime(int n) {
  6.     if (n <= 1) return false;
  7.     if (n <= 3) return true;
  8.     if (n % 2 == 0 || n % 3 == 0) return false;
  9.     for (int i = 5; i * i <= n; i += 6) {
  10.         if (n % i == 0 || n % (i + 2) == 0)
  11.             return false;
  12.     }
  13.     return true;
  14. }
  15. signed main() {
  16.     string T;
  17.     cin >> T;
  18.     int a = T.length();
  19.     int nguyenthanhluu = -1;
  20.     for (int i = 0; i < a; i++) {
  21.         int ngu = 0; 
  22.         for (int j = i; j < a; j++) {
  23.             if (T[j] < '0' || T[j] > '9') break;
  24.             ngu = ngu * 10 + (T[j] - '0');
  25.             if (ngu >= 1e8) break;
  26.             if (isPrime(ngu) ) {
  27.                 nguyenthanhluu = max(nguyenthanhluu,ngu);
  28.             }
  29.         }
  30.     }
  31.     cout << nguyenthanhluu << endl;
  32.     return 0;
  33. }
  34.  
Success #stdin #stdout 0.01s 5308KB
comments (?)
stdin 
Test1234#password5426
stdout 
23
https://ideone.com/3ObiEA
language:
C++14 (clang 8.0)
created:
267 days ago
visibility:
secret

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