import java.io.*;
import java.util.*;

public class Main {
    public static void main(String args[]) {
        String s;

        Scanner sc = new Scanner(System.in);
        s = sc.nextLine();

        Scanner scn = new Scanner(s);

        Stack<Integer> stack = new Stack<Integer>();

        while (scn.hasNext()) {
            String op = scn.next();
            if (op.equals("+")) {
                int n = stack.pop() + stack.pop();
                stack.push(n);
            } else if (op.equals("-")) {
                int n = -1 * stack.pop() + stack.pop();
                stack.push(n);
            } else if (op.equals("*")) {
                int n = stack.pop() * stack.pop();
                stack.push(n);
            } else {
                stack.push(Integer.parseInt(op));
            }
        }

        System.out.println(stack.pop());
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz