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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define int long long
  4. bool isprime(int n)
  5. {
  6.     if(n<=1)
  7.         return 0;
  8.     if(n==2)
  9.         return 1;
  10.     if(n%2==0)
  11.         return 0;
  12.     for(int i=3;i*i<=n;i+=2)
  13.         if(n%i==0)
  14.             return 0;
  15.     return 1;
  16. }
  17. signed main()
  18. {
  19.     int n;
  20.     cin>>n;
  21.     if(isprime(n))
  22.         cout<<"1\n"<<n;
  23.     else if(isprime(n-2))
  24.         cout<<"2\n2 "<<n-2;
  25.     else
  26.     {
  27.         cout<<"3\n";
  28.         cout<<3<<' ';
  29.         n-=3;
  30.         for(int i=3;i<n;i++)
  31.         {
  32.             bool b=0;
  33.             for(int ii=3;ii<n;ii++)
  34.             {
  35.                 if(isprime(i)&&isprime(ii)&&ii+i==n)
  36.                 {
  37.                     cout<<i<<' '<<ii;
  38.                     b=1;
  39.                     break;
  40.                 }
  41.             }
  42.             if(b)
  43.                 break;
  44.         }
  45.     }
  46. }
Success #stdin #stdout 0s 5284KB
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https://ideone.com/RpDWAp
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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