#include <stdio.h>
#include <stdlib.h>

int top, S[1000];

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

int pop() {
	top--;
	return S[top + 1];
}

int main(void) {
	int a, b, ch;
	top = 0;

	while ((ch = getchar()) != EOF && ch != '\n') {
		if (ch == '+') {
			a = pop();
			b = pop();
			push(a + b);
		}
		else if (ch == '-') {
			b = pop();
			a = pop();
			push(a - b);
		}
		else if (ch == '*') {
			a = pop();
			b = pop();
			push(a * b);
		}
		else if (ch == ' ') {
		}
		else{
			push(ch-48);
		}
	}

	printf("%d\n", pop());
	return 0;
}