#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;
}
