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

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

