diff --git a/panduan.c b/panduan.c
new file mode 100644
index 0000000..9e61ee7
--- /dev/null
+++ b/panduan.c
@@ -0,0 +1,82 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+void print_sudoku(char sudoku[9][9]) {
+    for (int i = 0; i < 9; i++) {
+        if (i % 3 == 0 && i != 0) {
+            printf("-------------------------\n");
+        }
+        for (int j = 0; j < 9; j++) {
+            if (j % 3 == 0 && j != 0) {
+                printf("| ");
+            }
+            printf("%c ", sudoku[i][j]);
+        }
+        printf("\n");
+    }
+}
+
+bool is_valid_sudoku(char sudoku[9][9]) {
+    // Check rows
+    for (int i = 0; i < 9; i++) {
+        int seen[9] = { 0 };
+        for (int j = 0; j < 9; j++) {
+            if (sudoku[i][j] != '.' && seen[sudoku[i][j] - '1'] == 1) {
+                printf("False: Invalid initial Sudoku matrix! The number %c in row %d has been used!\n", sudoku[i][j], i + 1);
+                return false;
+            }
+            seen[sudoku[i][j] - '1'] = 1;
+        }
+    }
+
+    // Check columns
+    for (int j = 0; j < 9; j++) {
+        int seen[9] = { 0 };
+        for (int i = 0; i < 9; i++) {
+            if (sudoku[i][j] != '.' && seen[sudoku[i][j] - '1'] == 1) {
+                printf("False: Invalid initial Sudoku matrix! The number %c in col %d has been used!\n", sudoku[i][j], j + 1);
+                return false;
+            }
+            seen[sudoku[i][j] - '1'] = 1;
+        }
+    }
+
+    // Check 3x3 blocks
+    for (int block = 0; block < 9; block++) {
+        int seen[9] = { 0 };
+        for (int i = block / 3 * 3; i < block / 3 * 3 + 3; i++) {
+            for (int j = block % 3 * 3; j < block % 3 * 3 + 3; j++) {
+                if (sudoku[i][j] != '.' && seen[sudoku[i][j] - '1'] == 1) {
+                    printf("False: Invalid initial Sudoku matrix! The number %c in block %d has been used!\n", sudoku[i][j], block + 1);
+                    return false;
+                }
+                seen[sudoku[i][j] - '1'] = 1;
+            }
+        }
+    }
+
+    printf("True: Valid initial Sudoku matrix!\n");
+    return true;
+}
+
+int main() {
+    char sudoku_board[9][9] = {
+        {'5', '3', '.', '.', '7', '.', '.', '.', '.'},
+        {'6', '.', '.', '1', '9', '5', '.', '.', '.'},
+        {'.', '9', '8', '.', '.', '.', '.', '6', '.'},
+        {'8', '.', '.', '.', '6', '.', '.', '.', '3'},
+        {'4', '.', '.', '8', '.', '3', '.', '.', '1'},
+        {'7', '.', '.', '.', '2', '.', '.', '.', '6'},
+        {'.', '6', '.', '.', '.', '.', '2', '8', '.'},
+        {'.', '.', '.', '4', '1', '9', '.', '.', '5'},
+        {'.', '.', '.', '.', '8', '.', '.', '7', '9'}
+    };
+
+
+    printf("The original Sudoku matrix: \n");
+    print_sudoku(sudoku_board);
+
+    is_valid_sudoku(sudoku_board);
+
+    return 0;
+}