using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Numerics; using System.Text; using static System.Console; using static System.Convert; using static System.Math; using static Extentions; class IO { int idx; string[] input = In.ReadToEnd().Split(new[] { " ", "\n", "\r" }, StringSplitOptions.RemoveEmptyEntries); T Get(Func parser) => parser(input[idx++]); public string S => Get(s => s); public char C => Get(char.Parse); public int I => Get(int.Parse); public long L => Get(long.Parse); public double F => Get(double.Parse); public decimal D => Get(decimal.Parse); public BigInteger B => Get(BigInteger.Parse); T[] Gets(int n, Func parser) => input.Skip((idx += n) - n).Take(n).Select(parser).ToArray(); public string[] Ss(int n) => Gets(n, s => s); public char[] Cs(int n) => Gets(n, char.Parse); public int[] Is(int n) => Gets(n, int.Parse); public long[] Ls(int n) => Gets(n, long.Parse); public double[] Fs(int n) => Gets(n, double.Parse); public decimal[] Ds(int n) => Gets(n, decimal.Parse); public BigInteger[] Bs(int n) => Gets(n, BigInteger.Parse); public void Write(params T[] xs) => WriteLine(string.Join(" ", xs)); public void Write(params object[] xs) => WriteLine(string.Join(" ", xs)); } struct Rational : IComparable, IEquatable { BigInteger numer; BigInteger denom; public BigInteger Numer { get { this.Reduce(); return numer; } } public BigInteger Denom { get { this.Reduce(); return denom; } } public int Sign => numer.CompareTo(0) * denom.CompareTo(0); public Rational(BigInteger numer, BigInteger denom) { this.numer = numer; this.denom = denom; } void Reduce() { if (numer == 0) { denom = 1; return; } var d = Gcd(numer, denom); numer /= d; denom /= d; if (denom < 0) { numer *= -1; denom *= -1; } } public Rational Invert() => new Rational(denom, numer); public static Rational operator -(Rational r) => new Rational(-r.numer, r.denom); public static Rational operator +(Rational left, Rational right) { left.Reduce(); right.Reduce(); var d = Lcm(left.denom, right.denom); var n = left.numer * d / left.denom + right.numer * d / right.denom; return new Rational(n, d); } public static Rational operator *(Rational left, Rational right) { left.Reduce(); right.Reduce(); var n = left.numer * right.numer; var d = left.denom * right.denom; return new Rational(n, d); } public static Rational operator -(Rational left, Rational right) => left + -right; public static Rational operator /(Rational left, Rational right) => left * right.Invert(); public static bool operator ==(Rational left, Rational right) => left.Equals(right); public static bool operator !=(Rational left, Rational right) => !left.Equals(right); public static bool operator <(Rational left, Rational right) => left.CompareTo(right) < 0; public static bool operator >(Rational left, Rational right) => left.CompareTo(right) > 0; public static bool operator <=(Rational left, Rational right) => left < right || left == right; public static bool operator >=(Rational left, Rational right) => left > right || left == right; public static implicit operator Rational(BigInteger x) => new Rational(x, 1); public int CompareTo(Rational other) => (this - other).Sign; public bool Equals(Rational other) { var r = this / other; return r.numer == r.denom; } public override bool Equals(object obj) { if (!(obj is Rational)) return false; var r = (Rational)obj / this; return r.numer == r.denom; } public override int GetHashCode() => this.Numer.GetHashCode() ^ this.Denom.GetHashCode(); public override string ToString() => $"{this.Numer} / {this.Denom}"; } static class Extentions { public static BigInteger Gcd(BigInteger x, BigInteger y) => BigInteger.GreatestCommonDivisor(x, y); public static BigInteger Lcm(BigInteger x, BigInteger y) => x * y / Gcd(x, y); } static class Program { public static void Main() { var sw = new StreamWriter(OpenStandardOutput()) { NewLine = "\n" }; #if DEBUG sw.AutoFlush = true; #else sw.AutoFlush = false; #endif SetOut(sw); Solve(new IO()); Out.Flush(); } static void Solve(IO io) { var n = io.I; var z = io.Bs(n); var t = new Rational(1, 1); for (var i = 0; i < n - 1; i++) t = t * z[i] / z[i + 1]; var gr = new BigInteger(1) / t; io.Write(gr.Numer + "/" + gr.Denom); } }