#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int top = 0; S[1000];
void push(int x){
	S[++top] = x;
}
int pop(void){
	top--;
	return S[top+1];
}
int main(void){
	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;
}
