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

int S[1000];
int top = 0;

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

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

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] == '-')
		{
			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());
}
