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

int top = 0, S[1000];

void push(int x) {
	S[++top] = x;
}
/* S[top++] = x ??£??\????????????top????¢???????
   S[++top] = x top????¢??????????????????£??\ */

int pop() {
	top--;
	/* printf("top: %d\n",top);  ?£??¶? */
	return S[top+1];
}

int main(void) {
	int a,b;
	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] == '*') {
			b = pop();
			a = pop();
			push(a * b);
		} else {
			push(atoi(s));
		}
	}
	
	printf("%d\n",pop());
	
	return 0;
}