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

int top, S[1000];

void push(int x)
{
	S[top] = x;
	top++;
}

int pop()
{
	top--;
	return S[top];
}

int main()
{
	top = 0;
	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] == '-')
		{
			a = pop();
			b = pop();
			push(b - a);
		}

		else if (s[0] == '*')
		{
			a = pop();
			b = pop();
			push(a * b);
		}

		else
			push(atoi(s));

	}

	printf("%d\n",pop());


	return 0;
}
