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

class Main {
	public static void main(String args[]) throws IOException{
		InputStreamReader isr = new InputStreamReader(System.in);
		BufferedReader br = new BufferedReader(isr);
		
		
		
		String str = br.readLine();
		String[] stA = (str.replaceAll("\\s+", " ")).split(" ", 0);
		
		//str.replaceAll("\\s+", " ") ??§??£?¶???????????????????????????????????????????????????????
		//?¬?????????????????????????????????????split(" ", 0)?????§?????????????????????????????¨??????????????????String???????????????
		
		Stack<String> stack = new Stack<String>();
		
		for(int i = 0; i < stA.length; i++) {
			if(stA[i].equals("+")) {
				//
				int a = new Integer(stack.pop().toString()).intValue();
				int b = new Integer(stack.pop().toString()).intValue();
				
				stack.push(String.valueOf(b+a));
				
			} else if(stA[i].equals("-")) {
				int a = new Integer(stack.pop().toString()).intValue();
				int b = new Integer(stack.pop().toString()).intValue();
				
				stack.push(String.valueOf(b-a));
				
			} else if(stA[i].equals("*")) {
				int a = new Integer(stack.pop().toString()).intValue();
				int b = new Integer(stack.pop().toString()).intValue();
				
				stack.push(String.valueOf(b*a));
				
			} else {
				stack.push(stA[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