
#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,0) != 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;
}

