#include<math.h>
int isPrime(long int a)
{
int loops=3;
int tt=sqrt(a)+1;
if ((a==1)||(a==0))
return 0;
else if(a==2)
return 1;
else if(a>=3)
{
if(a%2==0)
return 0;
for(loops=3;loops<=tt;loops+=2)
{
if(a%loops==0)
return 0;
}
return 1;
}
}
int main()
{
long int input=0;
printf("Please input a number：");
scanf("%d",&input);
if(isPrime(input)==1)
printf("It is a prime number.\n");
else
printf("It's not a prime number.\n");
system("PAUSE");
}
