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

int top, stack[1000];

void push(int);
int pop(void);

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

  printf("%d\n", pop());
  
  return 0;
}

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

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