diff --git a/f3.c b/f3.c
new file mode 100644
index 0000000..915b5a1
--- /dev/null
+++ b/f3.c
@@ -0,0 +1,140 @@
+#include <stdio.h>
+
+
+int checkRows(int matrix[9][9]) {
+    for (int i = 0; i < 9; i++) {
+        int count[10] = {0};
+        for (int j = 0; j < 9; j++) {
+            if (matrix[i][j] >= 1 && matrix[i][j] <= 9) {
+                if (count[matrix[i][j]] == 1) {
+                    return 0;
+                }
+                count[matrix[i][j]]++;
+            }
+        }
+    }
+    return 1;
+}
+
+
+int checkColumns(int matrix[9][9]) {
+    for (int j = 0; j < 9; j++) {
+        int count[10] = {0};
+        for (int i = 0; i < 9; i++) {
+            if (matrix[i][j] >= 1 && matrix[i][j] <= 9) {
+                if (count[matrix[i][j]] == 1) {
+                    return 0;
+                }
+                count[matrix[i][j]]++;
+            }
+        }
+    }
+    return 1;
+}
+
+
+int checkSubMatrices(int matrix[9][9]) {
+    for (int blockRow = 0; blockRow < 3; blockRow++) {
+        for (int blockCol = 0; blockCol < 3; blockCol++) {
+            int count[10] = {0};
+            for (int i = blockRow * 3; i < blockRow * 3 + 3; i++) {
+                for (int j = blockCol * 3; j < blockCol * 3 + 3; j++) {
+                    if (matrix[i][j] >= 1 && matrix[i][j] <= 9) {
+                        if (count[matrix[i][j]] == 1) {
+                            return 0;
+                        }
+                        count[matrix[i][j]]++;
+                    }
+                }
+            }
+        }
+    }
+    return 1;
+}
+
+
+void printMatrix(int matrix[9][9]) {
+	printf("|--------------------|\n|");
+    for (int i = 0; i < 9; i++) {
+        for (int j = 0; j < 9; j++) {
+            printf("%d ", matrix[i][j]);
+            if((i+1)%1==0&&(j+1)%3==0) printf("|");
+ if((i+1)%3==0&&(j+1)%9==0) printf("\n|--------------------|");
+ if((j+1)==9&&i!=8) printf("\n|");
+        }
+        
+    }
+}
+
+int main() {
+    int matrix[9][9] = {
+        {5, 3, 0, 0, 7, 0, 0, 0, 0},
+        {6, 0, 0, 1, 9, 5, 0, 0, 0},
+        {0, 9, 8, 0, 0, 0, 0, 6, 0},
+        {8, 0, 0, 0, 6, 0, 0, 0, 3},
+        {4, 0, 0, 8, 0, 3, 0, 0, 1},
+        {7, 0, 0, 0, 2, 0, 0, 0, 6},
+        {0, 6, 0, 0, 0, 0, 2, 8, 0},
+        {0, 0, 0, 4, 1, 9, 0, 0, 5},
+        {0, 0, 0, 0, 8, 0, 0, 7, 9}
+    };
+
+  
+    printf("The original Sudoku matrix: \n");
+    printMatrix(matrix);
+
+   
+    if (checkRows(matrix) && checkColumns(matrix) && checkSubMatrices(matrix)) {
+        printf("True:Valid initial Sudoku matrix!\n");
+    } else {
+        printf("False:Invalid initial Sudoku matrix!\n");
+
+      
+        for (int i = 0; i < 9; i++) {
+            int count[10] = {0};
+            for (int j = 0; j < 9; j++) {
+                if (matrix[i][j] >= 1 && matrix[i][j] <= 9) {
+                    if (count[matrix[i][j]] == 1) {
+                        printf("The number %d in the row %d has been used!\n", matrix[i][j], i + 1);
+                        
+                    }
+                    count[matrix[i][j]]++;
+                }
+            }
+        }
+
+        
+        for (int j = 0; j < 9; j++) {
+            int count[10] = {0};
+            for (int i = 0; i < 9; i++) {
+                if (matrix[i][j] >= 1 && matrix[i][j] <= 9) {
+                    if (count[matrix[i][j]] == 1) {
+                        printf("The number %d in the col %d has been used!\n", matrix[i][j], j + 1);
+                        
+                    }
+                    count[matrix[i][j]]++;
+                }
+            }
+        }
+
+        
+        for (int blockRow = 0; blockRow < 3; blockRow++) {
+            for (int blockCol = 0; blockCol < 3; blockCol++) {
+                int count[10] = {0};
+                for (int i = blockRow * 3; i < blockRow * 3 + 3; i++) {
+                    for (int j = blockCol * 3; j < blockCol * 3 + 3; j++) {
+                        if (matrix[i][j] >= 1 && matrix[i][j] <= 9) {
+                            if (count[matrix[i][j]] == 1) {
+                                printf("The number %d in the block %d has been used!\n", matrix[i][j], blockRow * 3 + blockCol + 1);
+                                
+                            }
+                            count[matrix[i][j]]++;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    return 0;
+}