改进求素数问题

还是求m到n之间的素数

#include <stdio.h>
#include <math.h>
int main(void)
{
    int m,n,i;
    while(scanf("%d %d",&m,&n)==2)
    {
        if(m>n)
        {
            int t=m;
            m=n;
            n=t;
        }
        int count=0;
        for(i=m;i<n;i++)
        {
            int a=2;
            if(i==2||i==3||i==5||i==7){
                printf("%d ",i);
                count++;
                continue;
            }
            if(i%2==0||i%3==0||i%5==0||i%7==0)
               continue;
            while(a<sqrt(i))
            {
                if(i%a==0)
                {
                    break;
                }
                a++;
            }
            if(a>=sqrt(i))
            {
                printf("%d ",i);
                count++;
            }else
            continue;
            if(count%10==0)
            {
                printf("\n");
            }
        }
        printf("\n");
    }
}