package solutions //Returns the element of the slice that doesn't have a correspondant pair func Unmatch(arr []int) int { //count the number of repetitions of each value var quant int for _, el := range arr { quant = 0 for _, v := range arr { if v == el { quant++ } } //if the number of repetitions is odd return that element if quant%2 != 0 { return el } } return -1 }