#pragma warning disable IDE0011
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Text;
using static System.Convert;
using static System.Math;
using static Extentions;

class IO
{
    int idx;
    string[] line;

    public void R(params char[] sep) { line = Console.ReadLine().Split(sep); idx = 0; }
    public string S => line[idx++];
    public string[] Ss => line.Skip(idx++).ToArray();
    public char C => char.Parse(line[idx++]);
    public char[] Cs => line.Skip(idx++).Select(char.Parse).ToArray();
    public int I => int.Parse(line[idx++]);
    public int[] Is => line.Skip(idx++).Select(int.Parse).ToArray();
    public long L => long.Parse(line[idx++]);
    public long[] Ls => line.Skip(idx++).Select(long.Parse).ToArray();
    public double F => double.Parse(line[idx++]);
    public double[] Fs => line.Skip(idx++).Select(double.Parse).ToArray();
    public decimal D => decimal.Parse(line[idx++]);
    public decimal[] Ds => line.Skip(idx++).Select(decimal.Parse).ToArray();
    public BigInteger B => BigInteger.Parse(line[idx++]);
    public BigInteger[] Bs => line.Skip(idx++).Select(BigInteger.Parse).ToArray();

    public void Write<T>(params T[] xs)
    {
        Console.Write(xs.First());
        foreach (var x in xs.Skip(1)) Console.Write(" " + x);
        Console.WriteLine();
    }
    public void Write(params object[] xs)
    {
        Console.Write(xs.First());
        foreach (var x in xs.Skip(1)) Console.Write(" " + x);
        Console.WriteLine();
    }
}

static class Extentions
{
    public static long Gcd(long x, long y)
    {
        long r;
        while ((r = x % y) != 0) { x = y; y = r; }
        return y;
    }

    public struct Rational
    {
        long numerator;
        long denominator;

        public long Numerator
        {
            get { this.Reduce(); return numerator; }
            set { numerator = value; }
        }
        public long Denominator
        {
            get { this.Reduce(); return denominator; }
            set { if (value == 0) throw new DivideByZeroException(); denominator = value; }
        }

        public Rational(long numerator, long denominator)
        {
            this.numerator = numerator;
            this.denominator = denominator;
        }

        void Reduce()
        {
            if (numerator == 0) { denominator = 1; return; }
            var d = Gcd(numerator, denominator);
            numerator /= d; denominator /= d;
            if (denominator < 0) { numerator *= -1; denominator *= -1; }
        }

        public Rational Invert() => new Rational(denominator, numerator);

        public static Rational operator -(Rational r) => new Rational(-r.numerator, r.denominator);

        public static Rational operator +(Rational left, Rational right)
        {
            left.Reduce(); right.Reduce();
            var n = checked(right.denominator * left.numerator + left.denominator * right.numerator);
            var d = checked(left.denominator * right.denominator);
            return new Rational(n, d);
        }

        public static Rational operator -(Rational left, Rational right) => left + -right;

        public static Rational operator *(Rational left, Rational right)
        {
            left.Reduce(); right.Reduce();
            var n = checked(left.numerator * right.numerator);
            var d = checked(left.denominator * right.denominator);
            return new Rational(n, d);
        }

        public static Rational operator /(Rational left, Rational right) => left * right.Invert();

        public static bool operator ==(Rational left, Rational right)
        {
            var r = left / right;
            return r.numerator == r.denominator;
        }

        public static bool operator !=(Rational left, Rational right)
        {
            var r = left / right;
            return r.numerator != r.denominator;
        }

        public static implicit operator Rational(long x) => new Rational(x, 1);

        public override bool Equals(object obj)
        {
            if (!(obj is Rational)) return false;
            var r = (Rational)obj / this;
            return r.numerator == r.denominator;
        }

        public override int GetHashCode() => numerator.GetHashCode() ^ denominator.GetHashCode();
    }
}

static class Program
{
    public static void Main()
    {
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        Solve(new IO());
        Console.Out.Flush();
    }

    public static void Solve(IO io)
    {
        io.R();
        var b = io.Ls;

        var d = new Rational(b[0] * b[2] - b[1] * b[1], b[0] - b[1]);
        var r = b[0] != 0 ? -(d - b[1]) / b[0] : -(d - b[2]) / b[1];

        io.Write((r * b[2] + d).Numerator);
    }
}