Envío 1240

Código

/* Code by Eduardo Vega */
#include <stdio.h>
#include <stdlib.h>

int main ()
{
  long size = 0, num = 0, sum_right = 0, sum_left 
  = 0, i;
  long *array = NULL;
  long *arr_aux = NULL;

  scanf("%li", &size);
  array = malloc(sizeof(long int) * size);  
  arr_aux = malloc(sizeof(long int) * size);

  for (i = 0; i < size; i++)
  {
    scanf("%li", &num);    
    array[i] = num;       
    arr_aux[i] = num;    
  }

  for (i = size - 2; i > 0; i--)
      arr_aux[i] = arr_aux[i + 1] + array[i];

  for(i = 1; i < size; i++)
  {
    if (arr_aux[i] < 0 && arr_aux[i - 1] > 0)
    {
      printf("%li\n", i);
      free(array);
      return 0;
    }    
  }

  printf("Impossible\n");
  free(array);
  return 0;
}