#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 top = 0;
	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] == '-'){
			a = pop();
			b = pop();
			push(b - a);
		}else if(s[0] == '*'){
			a = pop();
			b = pop();
			push(a * b);
		}else{
			push(atoi(s));
		}
	}
	printf("%d\n", pop());
	return 0;
}