import java.util.Scanner;
import java.util.Stack;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Stack<Integer> st = new Stack<Integer>();
		String str = sc.nextLine();
		int x, y;
		for (String s : str.split(" ")) {
			if (s.equals("+") || s.equals("-") || s.equals("*")) {
				switch (s) {
				case "+":
					y = st.pop();
					x = st.pop();
					st.push(x + y);
					break;
				case "-":
					y = st.pop();
					x = st.pop();
					st.push(x - y);
					break;
				case "*":
					y = st.pop();
					x = st.pop();
					st.push(x * y);
					break;
				}
			} else {
				st.push(Integer.parseInt(s));
			}
		}
		System.out.println(st.pop());
		sc.close();
	}
}


/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