#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define MAX 1000
int top,S[MAX];

void push(int);
int pop();

int main(){
  int x,a,b;
  char s[1000];

  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 {
      x = atoi(s);
      push(x);

    }
  }
  printf("%d\n",pop());

  return 0;
}

void push(int x){
  if(top == MAX-1){
    fprintf(stderr,"Overflow\n");
    exit(0);
  }
  S[++top]=x;
}

int pop(){
  if(top == 0){
    fprintf(stderr,"Underflow\n");
    exit(1);
  }
  top--;
  return S[top+1];
}

