func hasSameDigits(s string) bool {
for ;len(s)!=2; {
var t string
for i:=0; i<len(s)-1; i++ {
_s := (int(s[i]-48) + int(s[i+1]-48)) % 10
t += string(rune(_s+48))
}
s = t
}
return s[0] == s[1]
}