输入一个数，判断是不是素数

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
    int n,a;
    while(cin>>n)
    {
        a=0;
        if(n==2)
            {
                cout<<"is prime"<<endl;
                continue;
            }
        if(n<=1)
            {
                cout<<"no is prime"<<endl;
                continue;
            }
        int m=floor(sqrt(n)+0.5);
        for(int i=2;i<=m;i++)
            if(n%i==0)
            {
                cout<<"no is prime"<<endl;
                a=1;
                break;
            }
            if(a==0)
            cout<<"is prime"<<endl;
    }
    return 0;
}

素数判定