#include <stdlib.h>
#include <stdio.h>
#include<string.h>
int top,S[1000];
void push(int x)
{
  S[++top] = x;
} 
int pop()
{
  top--;
  return S[top+1];
}
int main()
{
    int a,b;
    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;
}

