func isValidIranianNationalCode(input string) bool { for i := 0; i < 10; i++ { if input[i] < '0' || input[i] > '9' { return false } } check := int(input[9] - '0') sum := 0 for i := 0; i < 9; i++ { sum += int(input[i]-'0') * (10 - i) } sum %= 11 return (sum < 2 && check == sum) || (sum >= 2 && check+sum == 11) } #467