boj4948(베르트랑공준)

solution4948.c

#include<stdio.h>
#include<math.h>
int odd(int x)
{
    int j,check;
    int sum=0;
    for (int i=x+1;i<=2*x;i++)
    {
        check=0;
        j=sqrt(i);
        for (int f=2;f<=j;f++)
        {
            if (i%f==0)
            {
                check=1;
                break;
            }
            else continue;
        }
        if (check==0) sum++;
    }
    return sum;
}
int main()
{
    int k;
    while (scanf("%d",&k) && k!=0)
    {
        printf("%d\n",odd(k));
    }
}