#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;
	top = 0;
	char s[1000];
	
	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;
}

