#include<stdio.h>
#include<math.h>
#include<string.h>

long n,m,p,i;
int j;
double ab;
int a[50010];

void divide1(long t)
{
     for (j=2;j<sqrt(t);j++)
     {
          while (t % j == 0)
          {
               if (a[j]==0) p++;
               a[j]++;
               t/=j;
          }
     }
     if (t>1)
       {
           if (a[t]==0) p++;
           a[t]++;
       }
}

void divide2(long t)
{
     for (j=2;j<sqrt(t);j++)
     {
         while (t % j == 0)
          {
               a[j]--;
               if (a[j]==0) p--;
               t/=j;
          }
     }
     if (t>1)
       {
           a[t]--;
           if (a[t]==0) p--;
       }

}

int main()
{
    scanf("%ld %ld", &n, &m);
    if (n - m < m) m = n-m;
    memset(a,0,sizeof(a));
    for (i=n;i>=n-m+1;i--)
    {
        divide1(i);
    }
    for (i=1;i<=m;i++)
    {
        divide2(i);
    }
    printf("%ld\n", p);
    return 0;
}

you use long t and sqrt(t) and t must be double e.g. use sqrt(double(t) ). btw, you get WA6 after I submitted yr code

Edited by author 26.04.2007 14:29