# Участник:Kachanov vv/MB1

Перейти к: навигация, поиск
```https://www.spoj.com/problems/MB1/
```
```#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

bool is_prime[2097152];
vector<size_t> prime;
vector<size_t> pprime;

bool is_palin(const string &s) {
auto t = s;
reverse(t.begin(), t.end());
return t == s;
}

int main() {
is_prime[2] = true;
for(size_t i = 3; i < 2097152; i+=2){
is_prime[i] = true;
}
for (size_t i = 3; i < 2097152; i += 2){
for (size_t j = i*i; j < 2097152 and is_prime[i]; j+=i){
is_prime[j] = false;
}
}

for(size_t i = 0; i < 2097152; i++)
if(is_prime[i]){
prime.push_back(i);
}

for(size_t i = 0; i < prime.size(); i++){
string s = to_string(prime[i]);
if(is_palin(s)) {
pprime.push_back(prime[i]);
}
}

int t;
cin >> t;
while(t--){
int n;
cin >> n;

size_t pprime_prod = 1;
for (size_t num = pprime[n - 1]; num; num /= 10 ){
size_t acc = num % 10;
if(acc){
pprime_prod *= num % 10;
}
}

cout << pprime[n - 1] << " " << prime[pprime_prod - 1] << endl;
}
return 0;
}```