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  1. #include <bits/stdc++.h> // ZENDA
  2. using namespace std;
  3. #define ll long long
  4. const ll lim=1e6+7;
  5. ll l,r;
  6. vector <ll> a,tmp;
  7. bool snt[lim];
  8. bool check(ll q){
  9.     ll tmp=0;
  10.     ll w=q;
  11.     while (q){
  12.         tmp*=10;
  13.         tmp+=q%10;
  14.         q/=10;
  15.     }
  16.     if (w==tmp) return 1;
  17.     return 0;
  18. }
  19. int main(){
  20.     cin.tie(nullptr)->sync_with_stdio(0);
  21.     #define F "test"
  22.     if (ifstream(F".inp")){
  23.         freopen(F".inp","r",stdin);
  24.         freopen(F".out","w",stdout);
  25.     }
  26.     cin>>l>>r;
  27.     snt[0]=snt[1]=1;
  28.     for (ll i=2;i*i<=lim;i++)
  29.         if (!snt[i])
  30.             for (ll j=i*i;j<=lim;j+=i)
  31.                 snt[j]=1;
  32.     ll st=sqrt(l)-1;
  33.     while (st*st<=r){
  34.         if (st*st>=l && st*st<=r)
  35.             a.push_back(st);
  36.         st++;
  37.     }
  38.     for (ll v:a)
  39.         if (!snt[v]) tmp.push_back(v);
  40.     ll res=0;
  41.     for (ll v:tmp)
  42.         if (check(v)) res++;
  43.     cout<<res;
  44.     return 0;
  45. }
Success #stdin #stdout 0.01s 5316KB
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stdout 
Standard output is empty
https://ideone.com/dngQwa
language:
C++14 (gcc 8.3)
created:
5 days ago
visibility:
public

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