Economical Polish ntn. Эк. вычисление RPN

package main

import "fmt"
import "strconv"

func main() {
    signs := make([]string, 0)
    chars := make([]string, 0)
    brcks := make([]string, 0)
    dict := make(map[string]string)

//delete expression that has already been used
    lex_cut := func(ptr bool) {
        if ptr != true {
                        brcks = brcks[:len(brcks)-1] //'('
            signs = signs[:len(signs)-1]  //'$'
            chars = chars[:len(chars)-2]   //'ab'
            brcks = brcks[:len(brcks)-1]     //')'
            return
        } else {
            chars = chars[:len(chars)-2]
            return
        }
    }
    j := 1
    var brcls, c, s, res int
    //var str string
    newj := strconv.Itoa(j)

    fmt.Scanf ("%d\n", &str)
    if len(str) == 1 { goto exit }

    for _, x := range str {
            switch {
            case x == '#':
                signs = append(signs, string(x))
                s++
                //fmt.Printf("-#-")
            case x == '$':
                signs = append(signs, string(x))
                s++
                //fmt.Printf("-$-")
            case x == '@':
                signs = append(signs, string(x))
                s++
                //fmt.Printf("-@-")
            case 'a' <= x && x <= 'z':
                chars = append(chars, string(x))
                c++
                //fmt.Printf("-a-")
            case x == '(':
                continue
            case x == ')':
                //fmt.Printf(">> ")
                brcks = append(brcks, string(x))
                brcls++
                min_expr := RPN_to_STD_notation(signs, chars, brcls)
                //check if it exists in dictionary
                _, ok := dict[min_expr]

                if ok {
                    //if exists -> delete
                    brcks = brcks[:len(brcks)-1]
                    signs = signs[:len(signs)-1]
                    chars := chars[:len(chars)-2]
                                        brcks = brcks[:len(brcks)-1]
                    chars[len(chars)-1] = string(newj)
                } else {
                    //else mark and add
                    dict[min_expr] = string(brcls)
                    lex_cut(ok)
                    chars = append(chars, string(brcls))
                    res++
                }

            }
        }
    }
    fmt.Printf("%d", res)
        exit:
    fmt.Printf("0")
}