#include<stdio.h>
#include<stdlib.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;
  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;
 
}