#include <iostream>
#include <vector>
// Function to check primality
bool isPrime(long long n) {
if (n < 2) return false;
if (n % 2 == 0 && n != 2) return false;
for (long long i = 3; i * i <= n; i += 2) {
if (n % i == 0) return false;
}
return true;
}
// Concatenate two integers
long long concat(int a, int b) {
std::string s = std::to_string(a) + std::to_string(b);
return stoll(s);
}
int main() {
// Generate primes up to a limit
int limit = 12; // you can increase this
std::vector<int> primes;
for (int i = 2; i <= limit; i++) {
if (isPrime(i)) primes.push_back(i);
}
// Check pairs
for (int i = 0; i < primes.size(); i++) {
for (int j = 0; j < primes.size(); j++) {
if (i == j) continue; // skip same prime if you want
long long num = concat(primes[i], primes[j]);
if (isPrime(num)) {
std::cout << primes[i] << " + " << primes[j]
<< " -> " << num << " is prime\n";
}
}
}
}
/*
run:
2 + 3 -> 23 is prime
2 + 11 -> 211 is prime
3 + 7 -> 37 is prime
3 + 11 -> 311 is prime
5 + 3 -> 53 is prime
7 + 3 -> 73 is prime
11 + 3 -> 113 is prime
*/
