#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 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;
}
