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


int top = 0;
int S[1000];


void push(int x);
int pop();

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

}
int pop()
{
	top--;
	return S[top+1];

}

int main(void)
{
	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] == '-')
		{
			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;
	
}



