#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(void)
{
	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] =='*')
		{
			b= pop();
			a= pop();
			push(a*b);
		}
		else
		{
			push(atoi(s));
		}
	}
	
	printf("%d\n",pop());
	
	return 0;
}