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

int S[1000];
int top = 0;

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

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


int main() {
	char s[100];
	int a, b;

	while (scanf("%s", &s) != EOF){
		if (s[0] == '+') {
			a = pop();
			b = pop();
			push(a + b);
		} else if(s[0] == '*'){
			a = pop();
			b = pop();
			push(a * b);
		}
		else if (s[0] == '-') {
			a = pop();
			b = pop();
			push(b - a);
		} else {
			push(atoi(s));
		}
	}

	printf("%d\n", pop());

	return 0;
}
