#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int  r[1000];
int top;


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

int pop(){
	top--;
	return r[top+1];
}
	
int main(void){
  int x,y;
  int top=0;
  char s[1000];
  while( scanf("%s", s) != EOF )
  {
    if ( s[0] == '+' ){
		x=pop();
		y=pop();
		push(x+y);
    } 
    else if ( s[0] == '-' )
    {
		x=pop();
		y=pop();
		push(y-x);
    }
    else if ( s[0] == '*' )
    {
		x=pop();
		y=pop();
		push(x*y);
    } 
    else
    {
      push(atoi(s));
    }
  }
   printf("%d\n", pop());
     
   return 0;
}
