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

int top, S[1000];

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

int pop(){
	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;

}
