#include "stdio.h"
#include "math.h"
int fun(int m)
{
int i;
for(i=2;i<=sqrt(m);i++)
{
if(m%i==0) return 0;
}
return 1;
}void main()
{ int m,k=0;
int n;
printf("input a number:");
scanf("%d",&n);
printf("小於%d的素數有:\n");
for(m=2;m<=n;m++)
{
if(fun(m))
{
printf("%4d",m);
k++;
if(k%5==0)
printf("\n");
}
}
}