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

int top;
int S[1000];

void push(int x){
	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;
}
		
		
		
	
		
	
