#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() {
	char s[100];
	int a, b;
	top = 0;

	while (scanf_s("%s", s, 1) != 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 {
			int i = stoi(s);
			push(i);
		}

	}
		printf("%d\n", pop());

	return 0;
}