diff --git a/3.txt b/3.txt
new file mode 100644
index 0000000..f2debaa
--- /dev/null
+++ b/3.txt
@@ -0,0 +1,93 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+int check(int sudoku[9][9]) {
+    int w[9], c[9], b[9];
+
+    for (int i = 0; i < 9; i++) {
+        for (int j = 0; j < 9; j++) {
+            w[j] = 0;
+            c[j] = 0;
+            b[j] = 0;
+        }
+
+        for (int j = 0; j < 9; j++) {
+            int k = sudoku[i][j];
+
+            if (k == 0) continue;
+            if (w[k - 1] == 1) return 0;
+            w[k - 1] = 1;
+
+            k = sudoku[j][i];
+
+            if (k == 0) continue;
+            if (c[k - 1] == 1) return 0;
+            c[k - 1] = 1;
+
+            k = sudoku[(i / 3) * 3 + j / 3][(i % 3) * 3 + j % 3];
+
+            if (k == 0) continue;
+            if (b[k - 1] == 1) return 0;
+            b[k - 1] = 1;
+        }
+    }
+
+    return 1;
+}
+
+int main() {
+    int a[9][9] = { 0 };
+    int i, j, k;
+
+    printf("The original Sudoku matrix:\n");
+    srand(time(NULL));
+    printf("|-------------------|\n");
+
+    for (i = 0; i < 9; i++) {
+        for (j = 0; j < 9; j++) {
+            if (j % 3 == 0) printf("|");
+
+            if (rand() % 3 == 0) {
+                do {
+                    k = rand() % 9 + 1;
+                } while (a[i][k - 1] != 0);
+
+                a[i][k - 1] = k;
+                printf("%d", k);
+            }
+            else {
+                a[i][j] = 0;
+                printf(".");
+            }
+
+            if (j == 8) printf("|");
+            printf(" ");
+        }
+
+        if ((i + 1) % 3 == 0) printf("\n|-------------------|");
+        printf("\n");
+    }
+
+    if (check(a))
+        printf("True: Valid initial Sudoku matrix!\n");
+    else {
+        printf("False: Invalid initial Sudoku matrix!\n");
+        for (i = 0; i < 9; i++) {
+            for (j = i + 1; j < 9; j++) {
+                for (k = i / 3 * 3; k < i / 3 * 3 + 3; k++) {
+                    for (int l = i % 3 * 3; l < i % 3 * 3 + 3; l++) {
+                        if ((a[i][j] != 0 && a[i][j] == a[k][l]) ||
+                            (a[j][i] != 0 && a[j][i] == a[l][k])) {
+                            printf("The number %d in the row %d has been used!\n", a[i][j], i + 1);
+                            goto end;
+                        }
+                    }
+                }
+            }
+        }
+    end:;
+    }
+
+    return EXIT_SUCCESS;
+}