a)
#include <iostream>
using namespace std;
bool Isp(int n){
if (n < 2) return 0;
if (n < 4) return 1;
if (n % 2 == 0 | n % 3 == 0) return 0;
for (int i = 5;i*i <= n;i += 6)
if (n % i == 0 | n % (i+2) == 0)
return 0;
return 1;
}
int main()
{
int n;
cin >> n;
if (Isp(i))
cout << "True";
else
cout << "False";
}
b)
#include <iostream>
using namespace std;
bool Isp(int n){
if (n < 2) return 0;
if (n < 4) return 1;
if (n % 2 == 0 | n % 3 == 0) return 0;
for (int i = 5;i*i <= n;i += 6)
if (n % i == 0 | n % (i+2) == 0)
return 0;
return 1;
}
int main()
{
int n;
int t = 0;
cin >> n;
if (n >= 2) t = 2;
for (int i = 3;i <= n;i += 2)
if (Isp(i))
t += i;
cout << t;
}
