Statistics

Problem Statement for "TheNumbersWithLuckyLastDigit"

Problem Statement

John believes that the digits 4 and 7 are lucky, and all other digits are unlucky. A positive integer is called a lucky number if its last digit is lucky. For example, 4, 14 and 207 are lucky numbers, while 40, 741 and 3 are not lucky numbers. John would like to represent the int n as a sum of only lucky numbers, and he would like to do this using the minimal possible number of summands. Return the number of summands in the representation, or -1 if it is impossible to achieve the goal.

Definition

Class:
TheNumbersWithLuckyLastDigit
Method:
find
Parameters:
int
Returns:
int
Method signature:
int find(int n)
(be sure your method is public)

Constraints

  • n will be between 1 and 1,000,000,000, inclusive.

Examples

  1. 99

    Returns: 4

    One of the possible representations is 99=14+24+27+34.

  2. 11

    Returns: 2

    11=4+7.

  3. 13

    Returns: -1

    It is impossible to achieve the goal.

  4. 1234567

    Returns: 1

  5. 1

    Returns: -1

  6. 2

    Returns: -1

  7. 3

    Returns: -1

  8. 4

    Returns: 1

  9. 5

    Returns: -1

  10. 6

    Returns: -1

  11. 7

    Returns: 1

  12. 8

    Returns: 2

  13. 9

    Returns: -1

  14. 10

    Returns: -1

  15. 11

    Returns: 2

  16. 12

    Returns: 3

  17. 13

    Returns: -1

  18. 14

    Returns: 1

  19. 15

    Returns: 3

  20. 16

    Returns: 4

  21. 17

    Returns: 1

  22. 18

    Returns: 2

  23. 19

    Returns: 4

  24. 20

    Returns: 5

  25. 21

    Returns: 2

  26. 22

    Returns: 3

  27. 23

    Returns: 5

  28. 24

    Returns: 1

  29. 25

    Returns: 3

  30. 26

    Returns: 4

  31. 27

    Returns: 1

  32. 28

    Returns: 2

  33. 29

    Returns: 4

  34. 30

    Returns: 5

  35. 757148

    Returns: 2

  36. 167851001

    Returns: 2

  37. 301413357

    Returns: 1

  38. 336971125

    Returns: 3

  39. 659598369

    Returns: 4

  40. 160567226

    Returns: 4

  41. 391749388

    Returns: 2

  42. 4890852

    Returns: 3

  43. 35766291

    Returns: 2

  44. 26239573

    Returns: 5

  45. 473038165

    Returns: 3

  46. 1000000000

    Returns: 5

  47. 999999999

    Returns: 4

  48. 42

    Returns: 3

  49. 100000000

    Returns: 5

  50. 909090900

    Returns: 5

  51. 100

    Returns: 5

  52. 50

    Returns: 5

  53. 10000

    Returns: 5

  54. 900

    Returns: 5

  55. 336

    Returns: 4

  56. 45

    Returns: 3

  57. 1000000

    Returns: 5

  58. 33

    Returns: 5

  59. 281

    Returns: 2

  60. 10000000

    Returns: 5

  61. 1555555

    Returns: 3

  62. 88

    Returns: 2

  63. 46

    Returns: 4

  64. 1001

    Returns: 2

  65. 20000

    Returns: 5

  66. 60

    Returns: 5

  67. 103

    Returns: 5

  68. 53

    Returns: 5

  69. 784783209

    Returns: 4

  70. 1000

    Returns: 5

  71. 2800

    Returns: 5

  72. 36

    Returns: 4

  73. 155555555

    Returns: 3

  74. 200

    Returns: 5

  75. 35

    Returns: 3

  76. 70

    Returns: 5

  77. 110

    Returns: 5

  78. 222

    Returns: 3

  79. 87

    Returns: 1

  80. 999999992

    Returns: 3

  81. 999999998

    Returns: 2

  82. 55

    Returns: 3

  83. 300000

    Returns: 5

  84. 9921

    Returns: 2

  85. 2000

    Returns: 5

  86. 38

    Returns: 2

  87. 220

    Returns: 5

  88. 952250

    Returns: 5

  89. 688606352

    Returns: 3

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