diff --git a/solutions/day04.go b/solutions/day04.go
index 75b9a6e..bde7bcd 100644
--- a/solutions/day04.go
+++ b/solutions/day04.go
@@ -2,6 +2,7 @@ package solutions
 
 import (
 	"regexp"
+	"strconv"
 	"strings"
 )
 
@@ -25,10 +26,10 @@ func Day04Part01(isTest bool) int {
 			values[key] = value
 		}
 
-		_, cidMissing := values["cid"]
+		_, cidPresent := values["cid"]
 		keysAmount := len(values)
 
-		if keysAmount == 8 || (keysAmount == 7 && !cidMissing) {
+		if keysAmount == 8 || (keysAmount == 7 && !cidPresent) {
 			correctAmount += 1
 		}
 	}
@@ -37,5 +38,117 @@ func Day04Part01(isTest bool) int {
 }
 
 func Day04Part02(isTest bool) int {
-	return -1
+	input := ReadInput("04", isTest)
+	passports := strings.Split(input, "\n\n")
+
+	regex, _ := regexp.Compile("[\\n\\s]")
+
+	correctAmount := 0
+
+	for _, passport := range passports {
+		matches := regex.Split(passport, -1)
+		// s := "hgt:59cm ecl:zzz\neyr:2038 hcl:74454a iyr:2023\npid:3556412378 byr:2007"
+		// matches = regex.FindAllString(s, -1)
+
+		values := make(map[string]string)
+
+		for _, match := range matches {
+			colonPosition := strings.Index(match, ":")
+			key := match[:colonPosition]
+			value := match[colonPosition+1:]
+			values[key] = value
+		}
+
+		if !validateByr(values) || !validateIyr(values) || !validateEyr(values) ||
+			!validateHgt(values) || !validateHcl(values) || !validateEcl(values) ||
+			!validatePid(values) {
+			continue
+		}
+
+		correctAmount += 1
+	}
+
+	return correctAmount
+}
+
+func validateYear(year string, min, max int) bool {
+	yearNumber, err := strconv.Atoi(year)
+	if err != nil {
+		return false
+	}
+
+	return min <= yearNumber && yearNumber <= max
+}
+
+func validateByr(values map[string]string) bool {
+	byr, _ := values["byr"]
+	return validateYear(byr, 1920, 2002)
+}
+
+func validateIyr(values map[string]string) bool {
+	byr, _ := values["iyr"]
+	return validateYear(byr, 2010, 2020)
+}
+
+func validateEyr(values map[string]string) bool {
+	byr, _ := values["eyr"]
+	return validateYear(byr, 2020, 2030)
+}
+
+func validateHgt(values map[string]string) bool {
+	height, ok := values["hgt"]
+	if !ok {
+		return false
+	}
+
+	cmIdx := strings.Index(height, "cm")
+	if cmIdx != -1 {
+		cm, err := strconv.Atoi(height[:cmIdx])
+		if err != nil {
+			return false
+		}
+
+		return 150 <= cm && cm <= 193
+	}
+	inIdx := strings.Index(height, "in")
+	if inIdx != -1 {
+		in, err := strconv.Atoi(height[:inIdx])
+		if err != nil {
+			return false
+		}
+
+		return 59 <= in && in <= 76
+	}
+
+	return false
+}
+
+func validateHcl(values map[string]string) bool {
+	hairColor, ok := values["hcl"]
+	if !ok {
+		return false
+	}
+
+	matched, _ := regexp.MatchString("#[a-f0-9]{6}", hairColor)
+	return matched
+}
+
+func validateEcl(values map[string]string) bool {
+	eyeColor, ok := values["ecl"]
+	if !ok {
+		return false
+	}
+
+	return eyeColor == "amb" || eyeColor == "blu" || eyeColor == "brn" ||
+		eyeColor == "gry" || eyeColor == "grn" || eyeColor == "hzl" || eyeColor == "oth"
+}
+
+func validatePid(values map[string]string) bool {
+	passportId, ok := values["pid"]
+	if !ok {
+		return false
+	}
+
+	matched, _ := regexp.MatchString("\\d{9}", passportId)
+	return matched
 }