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

int S[1000];
int top;
void push(int x){
  top ++;
  S[top]=x;
}
int pop(){
  top--;
  return S[top+1];
}

int main(){
  char s[100];
  int c,b,a,top=0;
  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 push(atoi(s));
  }
  printf("%d\n",pop());
  return 0;
}

