#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(void){
	
	int a,b;
	top=0;
	char s[100];
	int ans;
	
	
	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;
}
