import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Stack;

class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] str = br.readLine().split(" ");
		Stack<Integer> stack = new Stack<Integer>();

		for (int i = 0; i < str.length; i++) {
			if (str[i].equals("+")) {
				stack.push(stack.pop() + stack.pop());
			} else if (str[i].equals("-")) {
				int num01 = stack.pop();
				int num02 = stack.pop();
				stack.push(num02 - num01);
			} else if (str[i].equals("*")) {
				stack.push(stack.pop() * stack.pop());
			} else {
				stack.push(Integer.parseInt(str[i]));
			}
		}
		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