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

void push(int);
int pop(void);

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