#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()
{
	int a,b;
	char s[100];
	
	top = 0;
	
	while( scanf("%s",s) != EOF )
	{
		if( s[0] == '+' )
		{
			a = pop();
			b = pop();
			push(a + b);
		}
		else if( s[0] == '-' )
		{
			a = pop();
			b = 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;
}