• Source 
    1. #include <iostream>
    2. #include <vector>
    3. #include <algorithm>
    4. #include <math.h>
    5. using namespace std;
    6.  
    7. long long a, b;
    8. vector <long long> uocA;
    9. vector <long long> uocB;
    10.  
    11. void khoitaoUocA (long long n)
    12. {
    13. 	if (sqrt (n)*sqrt (n)==n) uocA.push_back(sqrt(n));
    14. 	for (int i=1; i<sqrt (n); i++)
    15. 	{
    16. 		if (n%i==0)
    17. 		{
    18. 			uocA.push_back(i);
    19. 			uocA.push_back(n/i);
    20. 		}
    21. 	}
    22. }
    23.  
    24. void khoitaoUocB (long long n)
    25. {
    26. 	if (sqrt (n)*sqrt (n)==n) uocB.push_back(sqrt(n));
    27. 	for (int i=1; i<sqrt (n); i++)
    28. 	{
    29. 		if (n%i==0)
    30. 		{
    31. 			uocB.push_back(i);
    32. 			uocB.push_back(n/i);
    33. 		}
    34. 	}
    35. }
    36.  
    37. int main ()
    38. {
    39. 	cin>>a>>b;
    40. 	if (a==b) cout<<"0";
    41. 	else
    42. 	{
    43. 		khoitaoUocA (a);
    44. 		khoitaoUocB (b);
    45. 		int kq=2000000;
    46. 		for (int i=uocB.size()-1; i>=0; i--)
    47. 		{
    48. 			for (int j=uocA.size()-1; j>=0; j--)
    49. 			{
    50. 				if (uocB[i]==uocA[j])
    51. 				{
    52. 					long long p1=uocB[i];
    53. 					long long p2=uocA[j];
    54. 					long long p1c=b/p1;
    55. 					long long p2c=a/p2;
    56.  
    57. 					int demB1=0;
    58. 					while (1)
    59. 					{
    60. 						if (p1c%5==0)
    61. 						{
    62. 							p1c=p1c/5;
    63. 							demB1++;
    64. 						}
    65. 						else if (p1c%3==0)
    66. 						{
    67. 							p1c=p1c/3;
    68. 							demB1++;
    69. 						}
    70. 						else if (p1c%2==0)
    71. 						{
    72. 							p1c=p1c/2;
    73. 							demB1++;
    74. 						}
    75. 						else break;
    76. 					}
    77. 					int demB2=0;
    78. 					while (1)
    79. 					{
    80. 						if (p2c%5==0)
    81. 						{
    82. 							p2c=p2c/5;
    83. 							demB2++;
    84. 						}
    85. 						else if (p2c%3==0)
    86. 						{
    87. 							p2c=p2c/3;
    88. 							demB2++;
    89. 						}
    90. 						else if (p2c%2==0)
    91. 						{
    92. 							p2c=p2c/2;
    93. 							demB2++;
    94. 						}
    95. 						else break;
    96. 					}
    97. 					if (p1c==1 && p2c==1) kq = min (kq, demB1+demB2);
    98. 					break;
    99. 				}
    100. 			}
    101. 		}
    102. 		if (kq==2000000) cout<<"-1";
    103. 		else cout<<kq;
    104. 	}
    105.  
    106. 	return 0;
    107. }