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  1. #include <iostream>
  2.  
  3. using namespace std;
  4. int prim( long long  x ) {
  5.     int s = 0;
  6.     for( long long  i = 1; i <=  x ; i++ ) {
  7.         if( x % i == 0 ) {
  8.             s++;
  9.         }
  10.     }
  11.     if( s == 2 ) {
  12.         return 1;
  13.     }
  14.     return 0;
  15. }
  16.  
  17. int main() {
  18.     long long A = 600851475143;
  19.     long long i = 2;
  20.     long long C = 0;
  21.  
  22.     while( i < (A/2) ) {
  23.         while( A % i == 0  ) {
  24.             A = A / i;
  25.             if( i > C ) {
  26.                 C = i;
  27.             }
  28.         }
  29.         i++;
  30.     }
  31.     if (A > C) {
  32.     	C = A;
  33.     }
  34.     if( prim(C) ) {
  35.         cout<<C;
  36.     }
  37. 	return 0;
  38. }
Success #stdin #stdout 0s 3296KB
comments (?)
stdin 
Standard input is empty
stdout 
6857
https://ideone.com/OduLJA
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
public

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