hdu 2058 The sum problem

#include<stdio.h>
int main()
{
    int i,m,x,y,n,ans,num;
    while(~scanf("%d%d",&n,&m)&&n&&m)
    {
        ans=0;
        for(i=1; i<n; i++)
        {
            ans+=i;
            y=i;
            if(ans>=m) break;
        }
        if(ans==m) num=i;
        else num=i-1;

        for(i=num; i>0; i--)
        {

            x=(2*m/i-(i-1))/2;
            y=(2*m/i+(i-1))/2;
            if((x+y)*(y-x+1)==2*m)
                printf("[%d,%d]\n",x,y);
        }
        printf("\n");
    }
    return 0;
}