Secret Difference (APCS 2017-03 Beginner)

Points 100 1.0s 256M

For a positive integer in decimal notation, let \(A\) be the sum of the digits at odd positions and \(B\) be the sum of the digits at even positions. The absolute difference \(|A - B|\) is called the secret difference of this positive integer.

For example, for \(263541\), the sum of the digits at odd positions is \(A = 6 + 5 + 1 = 12\), and the sum of the digits at even positions is \(B = 2 + 3 + 4 = 9\), so the secret difference of \(263541\) is \(|12 - 9| = 3\).

Given a positive integer \(X\) in decimal notation, find the secret difference of \(X\).

Note: positions are counted from right to left; the units digit is position \(1\) (odd), the tens digit is position \(2\) (even), and so on.

Input

The input is a single line containing a positive integer \(X\) in decimal notation, followed by a newline character.

Constraints:

  • \(X\) is a positive integer with at most \(1000\) digits (i.e. \(1 \le X < 10^{1000}\))
  • \(X\) has no extra leading zeros

Output

Output the secret difference \(Y\) of \(X\) (in decimal notation), followed by a newline character.

Scoring

The time limit for each test case is \(1\) second; your score is the sum over the test cases you pass. The subtasks are:

  • Subtask 1 (\(20\) points): \(X\) has exactly four digits.
  • Subtask 2 (\(30\) points): \(X\) has at most \(9\) digits.
  • Subtask 3 (\(50\) points): \(X\) has at most \(1000\) digits.

Sample Input 1

263541

Sample Output 1

3

Sample Explanation 1

For \(263541\), \(A = 6 + 5 + 1 = 12\), \(B = 2 + 3 + 4 = 9\), and \(|A - B| = |12 - 9| = 3\).

Sample Input 2

131

Sample Output 2

1

Sample Explanation 2

For \(131\), \(A = 1 + 1 = 2\), \(B = 3\), and \(|A - B| = |2 - 3| = 1\).

Source

APCS programming exam, March 4, 2017, Problem 1.

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