using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;

class Program
{
    public void Proc()
    {
        Reader.IsDebug = false;
        int[] inpt = Reader.ReadLine().Split(' ').Select(a=>int.Parse(a)).ToArray();
        
        this.NumA = inpt[0];
        this.NumB = inpt[1];
        
        if(this.NumA + NumB == 0) {
            Console.WriteLine("0");
            return;
        }
        int ans = -1;
        for(int i=0; i<=(this.NumA + NumB)*2; i++) {
            int cntA = (int)(i*(double)NumA/100)-1;
            for(int j=cntA-1; j<=cntA+4; j++) {
                int tmpA = (int)Math.Round(j/(double)(i)*100, 0, MidpointRounding.AwayFromZero);
                int tmpB = (int)Math.Round((i-j)/(double)(i)*100, 0 , MidpointRounding.AwayFromZero);
                if(NumA == tmpA && NumB == tmpB) {
                    ans = i;
                    break;
                }
            }
            if(ans>=0) {
                break;
            }
        }
        Console.WriteLine(ans);

    }
    
    
    
    private int NumA;
    private int NumB;


    public class Reader
    {
        public static bool IsDebug = true;
        private static String PlainInput = @"


1 99



";
        private static System.IO.StringReader Sr = null;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (Sr == null)
                {
                    Sr = new System.IO.StringReader(PlainInput.Trim());
                }
                return Sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
    }
    static void Main()
    {
        Program prg = new Program();
        prg.Proc();
    }
}