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: Wrong Answer)

//  RAKSHIT KADAM
 #include <bits/stdc++.h>
 
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// #define ordered_set tree< int ,  null_type ,  less<int> ,  rb_tree_tag ,  tree_order_statistics_node_update>
 #warning !!!check the size of arrayss!!!
 #define ll long long
 #define int long long
 #define MOD  1000000007
 #define newMOD  998244353
 #define MAX 300006
 #define P(gg) for(auto rax:gg){cout<<rax<<" ";}cout<<endl;
 #define Need_for_speed(activated) ios_base :: sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL)
 #define satisfy ll t; cin>> t; while(t--)
 #define inp(n) int n;cin >> n
 #define mp make_pair
 #define pb push_back
 #define endl "\n"
 #define x first
 #define y second
 #define fore(i,a,b) for(ll i=a;i<b;i++)
 #define forci(i,n) for(ll i=0;i<n;i++)
 #define INF 2000000000000000005

 #define vi vector<ll>
#define pi 3.1415926535897932384626433832795
#define Endl endl
#define lb lower_bound
#define ub upper_bound

using namespace std;
//ll gcd(ll a, ll b){if (b == 0)return a;return gcd(b, a % b);}
//int power(int x, unsigned int y, unsigned int m){ if (y == 0) return 1;int p = power(x, y/2, m) % m;  p = (p * p) % m;                                                  return (y%2 == 0)? p : (x * p) % m;}
 //ddfdsfdfs

//ll modInverse(int a, int m){ return power(a, m-2, m);} // if a and m are relativelyprime

void solve()
{
    ll a,b;cin>>a>>b;
    ll price=(a*100)/8;ll i;
    ll lim=0;
    for( i=price;;i++)
    {
        if(i/10==b)break;
        if((i*8)/100!=a){lim=1;break;}
    }
    if(lim)cout<<"-1"<<endl;
    else
    cout<<i<<endl;
}
signed main()
{
 
   
    Need_for_speed(activated);
//satisfy
//    {
//   solve();
//    }


 solve();
    return 0;
}