第四章4

#include<stdio.h>
int main(void)
{
    int i,m;
    
    printf("Enter a number:");
    scanf("%d",&m);
    for(i=2;i<=m/2;i++)
        if(m%i==0)
        break;
    if(i>m/2&&m!=1)
        printf("%d is a prime number\n",m);
    else
        printf("No!\n");
        
    return 0;
}