#include using namespace std; int num(int n) { // Create a boolean array "prime[0..n]" and initialize // all entries it as true. A value in prime[i] will // finally be false if i is Not a prime, else true. bool prime[n+1];int k; memset(prime, true, sizeof(prime)); for (int p=2; p*p<=n; p++) { // If prime[p] is not changed, then it is a prime if (prime[p] == true) { // Update all multiples of p for (int i=p*2; i<=n; i += p) prime[i] = false; } } // Print all prime numbers for (int p=2; p<=n; p++){ if (prime[p]){k++;} } return k; } int main(){ int g,t,a,i,p; scanf("%d",&g); for(i=0;i