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

int top;
int S[1000];

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

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

int main(void) {
	int a, b;
	top = 0;
	char s[100];
	int count = 0;
	
	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));
		}
		if (getchar() == '\n') break;
	}
	printf("%d\n", pop());

	return 0;
}