add exit

+#include <iostream>
+#include <string>
+using namespace std;
+
+int main() {
+	cout << "[ ¿¡ÄÚ ÇÁ·Î±×·¥ ]" << endl;
+
+	while (1) {
+		cout << "input : ";
+		string i;
+		cin >> i;
+		cout << "echo : " << i << endl;
+		if (i == "exit") {
+			exit(1);
+		}
+	}
+
+	return 0;
+}
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