#include<stdio.h>
#include<stdlib.h>
#include<string.h> 
int top, S[1000];

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

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;
}