Find the price of a product before tax such that, when the consumption tax rate is 8 percent and 10 percent, the amount of consumption tax levied on it is A yen and B yen, respectively. (Yen is the currency of Japan.)

Here, the price before tax must be a positive integer, and the amount of consumption tax is rounded down to the nearest integer.

If multiple prices satisfy the condition, print the lowest such price; if no price satisfies the condition, print `-1`.

Constraints

* 1 \leq A \leq B \leq 100
* A and B are integers.

Input

Input is given from Standard Input in the following format:


A B


Output

If there is a price that satisfies the condition, print an integer representing the lowest such price; otherwise, print `-1`.

Examples

Input

2 2


Output

25


Input

8 10


Output

100


Input

19 99


Output

-1
#include<bits/stdc++.h>
using namespace std;
int main()
{
	int a,b;
	cin>>a>>b;
	int res,res2;
	for(int i=11;i<20000000;i++){
		res=(i*8)/100;
		res2=i/10;
		if(res==a&& res2==b){cout<<i<<endl;return 0;}
	}
	cout<<-1<<endl;
}
