#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;
top = 0;
char s[100];
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;

}
