#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) != 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;
}
