Please write wha am I getting CE:
// Boxes
#include <iostream.h>
#include <math.h>

int n, a, b;
long num=0;

int min(int a, int b)
{
 if (a<b) return a;
 else return b;
}

int c(int il)
{
 if (min(a, b)>il)
  return il+1;
 else return min(a, b)+1;
}

int count()
{
 int i;
 for (i=a+b; i>=0; i--)
 {
  num += c(min(i, a+b-i)) * long(pow(double(n), double(i)));
 }
 cout << num;
}

int main()
{
 cin >> n >> a >> b;
 count();
 return 0;
}

coercive conversion must like this (long)pow(n,i).
but your porgram is also WA.