#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int top,S[10000];

void push(int x);
int pop();
int main(void){
	int a,b;
	top=0;
	char s[1000];
	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(a*b);
		}else{
			push(atoi(s));
		}
	}
	printf("%d\n",pop());
	return 0;
}
void push(int x){
	S[++top]=x;
}
int pop(){
	top--;
	return S[top+1];
}
