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

int initialize(void);
int isEmpty(void);
int isFull(void);
void push(int);
int pop(void);

int top=0, S[100];

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

  while(scanf("%s", s) != EOF){

    if(s[0] == '+'){
      a = pop();
      b = pop();
      push(a + b);   /* top = 0 */
    }

    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", S[top]);
  return 0;
}

int isEmpty(void)
{
  if(top == 0) return 0;
  if(top != 0) return 1;
}

int isFull(void)
{
  if(top >= 100 - 1) return 0;
  else return 1;
}

void push(int x)
{
  if(isFull() == 1){
    top++;
    S[top] = x;
  }

}

int pop(void)
{
  if(isEmpty() == 1){
  top--;
  return S[top+1];
  }
}