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

void push(int);
int pop();

int top, N[1000];

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;
}

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

int pop(){
  top--;
  return N[top];
}

