View Code of Problem 27

#include <stdio.h>

int Issu(int n)
{
    if(n == 1 || n == 0)    return 0;
    if(n == 2)  return 1;
    int i ;
    for(i = 2;i <= n / 2;i++)
    {
        if(n % i == 0)
            return 0;
    }
    return 1;
}

int main(void)
{
    long long k = 2,arr[70000] = {0}, n = 69999;
    while(n--)
    {
        if(Issu(n) == 1)
            arr[n] = 1;
    }
    int a,b;
    while(scanf("%d%d",&a,&b) != EOF)
    {
        if(a > b)
        {
            int t = a;
            a = b;
            b = t;
        }
        long long sum = 0;
        for(k = a + 1;k < b;k++)
        {
            sum += ((arr[k] == 0) ? 0 : k);
        }
        printf("%lld\n",sum);
    }
    return 0;


}