#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int top,s[1000];

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

int pop(void){
	top--;
	return s[top+1];
}

main(){
	top=0;
	int a,b;
	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));
		}
		
	}
	printf("%d\n",pop());
}
