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

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String str = br.readLine();
    String[] stri = str.split(" ");
    Stack<Integer> st = new Stack<Integer>();
    for (int i = 0; i < stri.length; i++) {
      int i1, i2;
      switch (stri[i]) {
        case "+":
          i1 = st.pop();
          i2 = st.pop();
          st.push(i1 + i2);
          break;
        case "-":
          i1 = st.pop();
          i2 = st.pop();
          st.push(i2 - i1);
          break;
        case "*":
          i1 = st.pop();
          i2 = st.pop();
          st.push(i1 * i2);
          break;
        default:
          st.push(Integer.parseInt(stri[i]));
      }
    }
    System.out.println(st.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