#include <stdio.h>
#include <math.h>
void main()
{
    int x,i,k;
    printf("please enter a integer number:");
        scanf("%d",&x);              /*输入一个整数*/
        k=(int)sqrt(x);                 /*对M求平方根，再取整*/
        for (i=2;i<=k;i++)                 /*i作为除数*/
         if(x%i==0) break;                    /*如果m被i整除，m肯定不是素数*/
            if(i>k) printf("%d is a prime number\n",m);
                else printf("%d is not a prime number\n",m);
}