A. Game 23
time limit per test1 second
memory limit per test256 megabytes
inputstandard input
outputstandard output
Polycarp plays “Game 23”. Initially he has a number n and his goal is to transform it to m. In one move, he can multiply n by 2 or multiply n by 3. He can perform any number of moves.
Print the number of moves needed to transform n to m. Print -1 if it is impossible to do so.
It is easy to prove that any way to transform n to m contains the same number of moves (i.e. number of moves doesn’t depend on the way of transformation).
Input
The only line of the input contains two integers n and m (1≤n≤m≤5⋅108).
Output
Print the number of moves to transform n to m, or -1 if there is no solution.
Examples
inputCopy
120 51840
outputCopy
7
inputCopy
42 42
outputCopy
0
inputCopy
48 72
outputCopy
-1
Note
In the first example, the possible sequence of moves is: 120→240→720→1440→4320→12960→25920→51840. The are 7 steps in total.
In the second example, no moves are needed. Thus, the answer is 0.
In the third example, it is impossible to transform 48 to 72.
#include <bits/stdc++.h>
using
namespace std;
typedef long long LL;
int main()
{
int n, m;
cin >> n >> m;
if (m % n != 0)
cout << -1 << endl;
else
{
int cnt = 0;
int t = m / n;
while (t % 2 == 0)
t /= 2, cnt++;
while (t % 3 == 0)
t /= 3, cnt++;
if (t != 1)
cout << -1 << endl;
else
cout << cnt << endl;
}
return 0;
}