Problem:
Score : 300 points

Problem Statement

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.

Sample Input 1

2 2

Sample Output 1

25

If the price of a product before tax is 25 yen, the amount of consumption tax levied on it is:

When the consumption tax rate is 8 percent: \lfloor 25 \times 0.08 \rfloor = \lfloor 2 \rfloor = 2 yen.

When the consumption tax rate is 10 percent: \lfloor 25 \times 0.1 \rfloor = \lfloor 2.5 \rfloor = 2 yen.

Thus, the price of 25 yen satisfies the condition. There are other possible prices, such as 26 yen, but print the minimum such price, 25.

Sample Input 2

8 10

Sample Output 2

100

If the price of a product before tax is 100 yen, the amount of consumption tax levied on it is:

When the consumption tax rate is 8 percent: \lfloor 100 \times 0.08 \rfloor = 8 yen.

When the consumption tax rate is 10 percent: \lfloor 100 \times 0.1 \rfloor = 10 yen.

Sample Input 3

19 99

Sample Output 3

-1

There is no price before tax satisfying this condition, so print -1.

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;
 
int main() {
  int A,B;
  cin>>A>>B;
  int hachi[1264];
  int juu[1012];
  for(int i=1;i<1264;i++){
    hachi[i]=i*0.08;
    //cout<<i<<"円 "<<hachi[i]<<endl;
  }
  for(int i=1;i<1012;i++){
    juu[i]=i*0.1;
    //cout<<i<<"円 "<<juu[i]<<endl;
  }
  bool hantei1=false;
  int atai_hachi=0;
  int count1=0;
  bool hantei2=false;
  int atai_juu=0;
  int count2=0;
  for(int i=1;i<1264;i++){
    if(hachi[i]==A){
      hantei1=true;
      atai_hachi=i;
      count1++;
    }
  }
  for(int i=1;i<1012;i++){
    if(juu[i]==B){
      hantei2=true;
      atai_juu=i;
      count2++;
    }
  }
  //cout<<count1<<" "<<count2<<endl;
  //cout<<hantei1<<" "<<hantei2<<endl;
  if(hantei1==true&&hantei2==true){
    //cout<<atai_hachi<<" "<<atai_juu<<endl;
    for(int i=atai_hachi-count1+1;i<atai_hachi+1;i++){
      for(int j=atai_juu-count2+1;j<atai_juu+1;j++){
        if(i==j){
          cout<<i<<endl;
          return 0;
        }
      }
    }
    cout<<-1<<endl;
  }else{
    cout<<-1<<endl;
  }
  return 0;
}