#include<stdio.h>
#include<string.h>
#include<stdlib.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] == '-'){
			a = pop();
			b = pop();
			push(b - a);
		}
		else if(s[0] == '*'){
			a = pop();
			b = pop();
			push(a * b); 
		} 
		else{
			push(atoi(s));
		}
	}
	int ans = pop();
	printf("%d\n",ans);
	return 0;
}
