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

void push(int);
int pop();

int top;
int stack[100];

int main(){
  int x,a,b,n;
  int 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{
	n = atoi(s);
	push(n);
      }
  }

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

  return 0;
}

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

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

