#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int top, S[1000];

void push(int x){
  top++;
  S[top] = x;
}

int pop(){
  top--;
  return S[top+1];
}

int main(void){
  int a, b;
  char s[100];
  top = 0;

  while (scanf("%s", s) != EOF) {
    if (s[0] == '+') {
      a = pop();
      b = pop();
      push(a+b);
    }
    else if (s[0] == '-') {
      a = pop();
      b = pop();
      push(b-a);
    }
    else if (s[0] == '*') {
      a = pop();
      b = pop();
      push(a*b);
    }
    else {
      push(atoi(s));
    }
  }
  
  printf("%d\n", pop());

  return 0;
}

