在杭电刷题2012出现wrong answer的情况，请各位帮个忙

#include<stdio.h>
#include<math.h>
int main()
{
    signed    int x,y,i,k,j;
    signed    int place,flag;
    while(scanf("%d%d",&x,&y)!=EOF)
    {
        place=0; flag=0;
        if(x==0&&y==0) break;
        for(i=x;i<=y;i++)
        {
            k=i^2+i+41;
            for(j=2;j<sqrt(k);j++)
            {
                if(k%j!=0) flag=1;
                else flag=0;
            }
            if(flag==1)    place++;
        }
        if(place==(y-x+1)) printf("OK\n");
        else printf("Sorry\n");
    }
        
    return 0;
}