package main

var s string
var pT int

// Ubuntu(12.04)/amd64
// go version devel +4fa98cce4290 Mon Oct 29 11:16:58 2012 -0400
func main() {
	s = "(())"
	pT = 0
	p()
}
func p() {
	if pT >= len(s) {
		return
	}
	if s[pT] == '(' {
		pT += 1
		p()
		if pT < len(s) && s[pT] == ')' {
			pT += 1
		} else {
			// comment following println() triggers "nosplit stack overflow"
			// otherwise it "works"
			println("problem", s)
			return
		}
		p()
	}
}