Notes

Template in C

Constraints

2 ≤ the number of operands in the expression ≤ 100
1 ≤ the number of operators in the expression ≤ 99
-1 × 109 ≤ values in the stack ≤ 109

Input

An expression is given in a line. Two consequtive symbols (operand or operator) are separated by a space character.

You can assume that +, - and * are given as the operator and an operand is a positive integer less than 106

Output

Print the computational result in a line.

Examples

Input

1 2 +


Output

3


Input

1 2 + 3 4 - *


Output

-3
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int top;
int S[1000];

void push(int x){
	S[++top] = x;//++x先赋值再自增 
} 

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));
		}
	}
	printf("%d\n",pop());
	
	return 0;
} 
