using System;
namespace demoNMLT
{
class myPrime
static bool check(int n)
if (n < 2)
return false;
}
if (n == 2) return true;
int i = 3;
while (i <= Math.Sqrt(n))
if (n % i == 0)
i = i + 2;
return true;
static int sumPrime(int n)
int res = 2;
return 0;
while (i < n)
if (check(i))
res = res + i;
return res;
static void Main(string[] args)
Console.WriteLine("Nhap n:");
int n;
n = int.Parse(Console.ReadLine());
int sum = sumPrime(n);
Console.WriteLine($"Tong cac so nguyen to nho hon {n}: {sum}");