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

int top, S[1000];

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

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

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

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

  printf("%d\n", S[top]);

  return 0;
}

