diff --git a/2023/1/main.cpp b/2023/1/main.cpp
index c2a8254..b8fe325 100644
--- a/2023/1/main.cpp
+++ b/2023/1/main.cpp
@@ -19,10 +19,10 @@ int main() {
 
 	int ret = 0;
 
-	string line;
-	for (;;) {
+	while (!cin.eof()) {
+		string line;
 		getline(cin, line);
-		if (cin.eof())
+		if (line.empty())
 			break;
 
 		int pi = INT_MAX, pl = -1, vi = 0, vl = 0;
diff --git a/2023/2/main-1.cpp b/2023/2/main-1.cpp
index 58173fb..2dffa50 100644
--- a/2023/2/main-1.cpp
+++ b/2023/2/main-1.cpp
@@ -5,28 +5,23 @@ int main() {
 	ios::sync_with_stdio(0);
 	cin.tie(0);
 
-	auto& cin = std::cin >> noskipws;
-
 	int ret = 0, id = 0;
 	bool isPossible = true;
 
-	for (;;) {
-		char c;
-		cin >> c;
-		switch (c) {
+	while (!cin.eof()) {
+		switch (cin.get()) {
 		case 'G':
-			cin >> c; cin >> c; cin >> c; cin >> c;
+			cin.ignore(4);
 			cin >> id;
 			break;
 		case ':': case ',': case ';':
 			if (!isPossible)
 				break;
-			cin >> c;
+			cin.ignore(1);
 			int n;
 			cin >> n;
-			cin >> c;
-			cin >> c;
-			switch (c) {
+			cin.ignore(1);
+			switch (cin.get()) {
 			case 'r':
 				if (n > 12)
 					isPossible = false;
@@ -42,16 +37,16 @@ int main() {
 			}
 			break;
 		case '\n':
-			if (cin.eof())
-				goto end;
-			if (isPossible)
+		case EOF:
+			if (isPossible) {
 				ret += id;
-			else
+				id = 0;
+			} else {
 				isPossible = true;
+			}
 			break;
 		}
 	}
 
-end:
 	cout << ret << '\n';
 }
diff --git a/2023/2/main-2.cpp b/2023/2/main-2.cpp
index 723cb2d..fc73df3 100644
--- a/2023/2/main-2.cpp
+++ b/2023/2/main-2.cpp
@@ -5,39 +5,32 @@ int main() {
 	ios::sync_with_stdio(0);
 	cin.tie(0);
 
-	auto& cin = std::cin >> noskipws;
-
 	int ret = 0, id = 0, r = 0, g = 0, b = 0;
 
-	for (;;) {
-		char c;
-		cin >> c;
-		switch (c) {
+	while (!cin.eof()) {
+		switch (cin.get()) {
 		case 'G':
-			cin >> c; cin >> c; cin >> c; cin >> c;
+			cin.ignore(4);
 			cin >> id;
 			break;
 		case ':': case ',': case ';':
-			cin >> c;
+			cin.ignore(1);
 			int n;
 			cin >> n;
-			cin >> c;
-			cin >> c;
-			switch (c) {
+			cin.ignore(1);
+			switch (cin.get()) {
 			case 'r': r = max(n, r); break;
 			case 'g': g = max(n, g); break;
 			case 'b': b = max(n, b); break;
 			}
 			break;
 		case '\n':
-			if (cin.eof())
-				goto end;
+		case EOF:
 			ret += r * g * b;
 			r = 0; g = 0; b = 0;
 			break;
 		}
 	}
 
-end:
 	cout << ret << '\n';
 }
diff --git a/2023/3/main-1.cpp b/2023/3/main-1.cpp
index c2c0ca6..281ce44 100644
--- a/2023/3/main-1.cpp
+++ b/2023/3/main-1.cpp
@@ -10,13 +10,13 @@ int main() {
 	cin.tie(0);
 
 	vector<string> lines;
-	do {
+	while (!cin.eof()) {
 		string line;
 		getline(cin, line);
 		if (line.empty())
 			break;
 		lines.push_back(line);
-	} while (!cin.eof());
+	}
 
 	int ret = 0;
 
diff --git a/2023/3/main-2.cpp b/2023/3/main-2.cpp
index dceb6e6..aabc936 100644
--- a/2023/3/main-2.cpp
+++ b/2023/3/main-2.cpp
@@ -10,13 +10,13 @@ int main() {
 	cin.tie(0);
 
 	vector<string> lines;
-	do {
+	while (!cin.eof()) {
 		string line;
 		getline(cin, line);
 		if (line.empty())
 			break;
 		lines.push_back(line);
-	} while (!cin.eof());
+	}
 
 	int ret = 0;