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

class Program
{
    public static IO IO = new IO();
    static void Main(string[] args)
    {
        string[] n = IO.STRING(' ');
        STACK<string> s = new STACK<string>(n.Count());
        for (int i = 0; i < n.Count(); i++)
        {
            if (n[i] == "+")
            {
                s.PUSH((int.Parse(s.POP()) + int.Parse(s.POP())).ToString());
            }
            else if (n[i] == "-")
            {
                int n1 = int.Parse(s.POP());
                int n2 = int.Parse(s.POP());
                s.PUSH((n2 - n1).ToString());
            }
            else if (n[i] == "*")
            {
                s.PUSH((int.Parse(s.POP()) * int.Parse(s.POP())).ToString());
            }
            else
            {
                s.PUSH(n[i]);
            }
        }
        IO.WRITE(s.POP());
        IO.FLUSH();
    }
}
#region STACK
namespace LIB
{
    public class STACK<T>
    {
        private int m, p;
        private T[] s;
        public STACK(int max) { m = max; s = new T[m]; CLEAR(); }
        public void CLEAR() { p = 0; }
        public int COUNT() { return p; }
        public T PEEK() { return s[p - 1]; }
        public T POP() { T r = PEEK(); p--; return r; }
        public void PUSH(T v) { s[p] = v; p++; }
    }
}
#endregion
namespace LIB
{
    public class IO
    {
        private const int WMAX = 1000;
        private StringBuilder S = new StringBuilder();
        private T R<T>(Func<string, T> f) { return f(Console.ReadLine()); }
        private T[] R<T>(Func<string, T> f, char c) { return STRING().Split(c).Select(f).ToArray(); }
        private T[] R<T>(Func<string, T> f, int l) { T[] r = new T[l]; for (int i = 0; i < l; i++) { r[i] = R(f); } return r; }
        private T[][] R<T>(Func<string, T> f, int l, char c) { T[][] r = new T[l][]; for (int i = 0; i < l; i++) { r[i] = R<T>(f, c); } return r; }
        private void W<T>(Func<T, string> f, T v, bool lf = true) { S.Append(f(v)); if (lf == true) { S.Append('\n'); } if (S.Length >= WMAX) { FLUSH(); } }
        public string STRING() { return R(s => s); }
        public string[] STRING(char c) { return R(s => s, c); }
        public string[] STRING(int l) { return R(s => s, l); }
        public string[][] STRING(int l, char c) { return R(s => s, l, c); }
        public int INT() { return R(int.Parse); }
        public int[] INT(char c) { return R(int.Parse, c); }
        public int[] INT(int l) { return R(int.Parse, l); }
        public int[][] INT(int l, char c) { return R(int.Parse, l, c); }
        public long LONG() { return R(long.Parse); }
        public long[] LONG(char c) { return R(long.Parse, c); }
        public long[] LONG(int l) { return R(long.Parse, l); }
        public long[][] LONG(int l, char c) { return R(long.Parse, l, c); }
        public double DOUBLE() { return R(double.Parse); }
        public double[] DOUBLE(char c) { return R(double.Parse, c); }
        public double[] DOUBLE(int l) { return R(double.Parse, l); }
        public double[][] DOUBLE(int l, char c) { return R(double.Parse, l, c); }
        public void WRITE(string s, bool lf = true) { W(v => v, s, lf); }
        public void WRITE(int s, bool lf = true) { W(v => v.ToString(), s, lf); }
        public void WRITE(long s, bool lf = true) { W(v => v.ToString(), s, lf); }
        public void WRITE(double s, bool lf = true) { W(v => v.ToString(), s, lf); }
        public void FLUSH() { Console.Write(S); S.Length = 0; }
    }
}

Measured memory_bytes: 9664