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

void push(int);
int pop();

int cnt;
int NUM[1000];

int main(){
  int x,y;
  char s[100];

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

    }
  }

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

  return 0;
}

void push(int x){
  NUM[cnt++] = x;
}

int pop(){
	return NUM[--cnt];
}

