The program fragment below performs binary search of an integer
number in an array that is sorted in a nondescending order:
Pascal 
C 
const
MAXN = 10000;
var
A: array[0..MAXN1] of integer;
N: integer;
procedure BinarySearch(x: integer);
var
p, q, i, L: integer;
begin
p := 0; { Left border of the search }
q := N1; { Right border of the search }
L := 0; { Comparison counter }
while p <= q do begin
i := (p + q) div 2;
inc(L);
if A[i] = x then begin
writeln('Found item i = ', i,
' in L = ', L, ' comparisons');
exit
end;
if x < A[i] then
q := i  1
else
p := i + 1
end
end;

#define MAXN 10000
int A[MAXN];
int N;
void BinarySearch(int x)
{
int p, q, i, L;
p = 0; /* Left border of the search */
q = N1; /* Right border of the search */
L = 0; /* Comparison counter */
while (p <= q) {
i = (p + q) / 2;
++L;
if (A[i] == x) {
printf("Found item i = %d"
" in L = %d comparisons", i, L);
return;
}
if (x < A[i])
q = i  1;
else
p = i + 1;
}
}

Before BinarySearch was called, N was set to some
integer number from 1 to 10000 inclusive and
array A was filled with a nondescending integer sequence.
It is known that the procedure has terminated with the message
"Found item i = XXX in L = XXX comparisons" with some
known values of i and L.
Your task is to write a program that finds all possible values of
N that could lead to such message. However, the number of
possible values of N can be quite big. Thus, you are asked to group all
consecutive Ns into intervals and write down only first and
last value in each interval.
Input
The input consists of a single line with two integers i
and L (0 ≤ i < 10000 and
1 ≤ L ≤ 14), separated by a space.
Output
On the first line of the output write the single
integer number K
representing the total number of intervals for possible values of N.
Then K lines shall follow listing those intervals in an ascending order.
Each line shall contain
two integers A_{i} and B_{i}
(A_{i} ≤ B_{i})
separated by a space, representing first and last value of the interval.
If there are no possible values of N exist, then the output
shall contain the single 0.
Samples
input  output 

9000 2
 0

10 3
 4
12 12
17 18
29 30
87 94

Problem Source: 20002001 ACM Northeastern European Regional Programming Contest