diff --git a/3.c b/3.c
new file mode 100644
index 0000000..8df8706
--- /dev/null
+++ b/3.c
@@ -0,0 +1,104 @@
+#include<stdio.h>
+void printmat(int board[9][9])
+{
+	int i,j;
+	for (i=0;i<9;i++)
+	{
+		if(i%3==0) printf("|-----------------------|\n");
+		for(j=0;j<9;j++)
+		{
+			if(j%3==0) printf(j==0?"|":" |");
+			printf(" %d",board[i][j]);
+		}
+		printf(" |\n");
+	}
+	printf("|-----------------------|\n");
+	return;
+}
+
+int main()
+{
+	int board[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}};
+	
+	int checkmat[9][2][2]={{{0,0},{3,3}},
+					{{0,3},{3,6}},
+					{{0,6},{3,9}},
+					{{3,0},{6,3}},
+					{{3,3},{6,6}},
+					{{3,6},{6,9}},
+					{{6,0},{9,3}},
+					{{6,3},{9,6}},
+					{{6,6},{9,9}}};
+	int i,j,k,p,num;
+	printf("The original Sudoku matrix\n");
+	printmat(board);
+	
+	
+	for (i=0;i<9;i++)
+	{
+		int flag[9] = {0,0,0,0,0,0,0,0,0};
+		for (j=0;j<9;j++)
+		{
+			if (board[i][j]!=0 )
+			{
+				if (flag[board[i][j]-1]==1)
+				{
+					printf("False:Invalid initial Sudoku matrix\n");
+					printf("      The number %d in the row %d has been used!\n",board[i][j],i+1);
+					return 0;
+				}
+				else flag[board[i][j]-1]=1;
+			}
+		}
+	}
+	
+	for (i=0;i<9;i++)
+	{
+		int flag[9] = {0,0,0,0,0,0,0,0,0};
+		for (j=0;j<9;j++)
+		{
+			if (board[j][i]!=0 )
+			{
+				if (flag[board[j][i]-1]==1)
+				{
+					printf("False:Invalid initial Sudoku matrix\n");
+					printf("      The number %d in the col %d has been used!\n",board[j][i],i+1);
+					return 0;
+				}
+				else flag[board[j][i]-1]=1;
+			}
+		}
+	}
+	
+	for (k=0;k<9;k++)
+	{
+		int flag[9] = {0,0,0,0,0,0,0,0,0};
+		for (i=checkmat[k][0][0];i<checkmat[k][1][0];i++)
+		{
+			for (j=checkmat[k][0][1];j<checkmat[k][1][1];j++)
+			{
+				if (board[i][j]!=0 )
+				{
+					if (flag[board[i][j]-1]==1)
+					{
+						printf("False:Invalid initial Sudoku matrix\n");
+						printf("      The number %d in the block %d has been used!\n",board[i][j],k+1);
+						return 0;
+					}
+					else flag[board[i][j]-1]=1;
+				}
+			}
+		}
+	}
+	printf("True:Valid initial Sudoku matrix!\n");
+	return 0;
+}
+