diff --git a/pset4/5-squares.c b/pset4/5-squares.c
new file mode 100644
index 0000000..c92ae81
--- /dev/null
+++ b/pset4/5-squares.c
@@ -0,0 +1,25 @@
+#include <stdio.h>
+
+// Function prototypes
+int dividable(int n);
+
+int main(void)
+{
+	// Initialize variables and get input
+	int n, sum = 0;
+	scanf("%d", &n);
+
+	for (int i = 1; i < n; i++) {
+		if (dividable(i)) {
+			sum += i;
+		}
+	}
+
+	printf("%d\n", sum * sum);
+
+	return 0;
+}
+
+int dividable(int n) {
+	return (n % 3 == 0 && n % 7 == 0) ? 1 : 0;
+}
diff --git a/pset4/6-graph.c b/pset4/6-graph.c
new file mode 100644
index 0000000..478bc7f
--- /dev/null
+++ b/pset4/6-graph.c
@@ -0,0 +1,71 @@
+#include <stdio.h>
+
+// Function prototypes
+void print_block(int n, int m); // Print the pattern
+// n: columns
+// m: rows
+void print_row(int n, int m); // Print a line of row, called bu print_block
+// n: number of columns m: position of row
+// n: number of columns, see print_column
+// m: ranging from 0 to 3
+// m == 0: |*****|*****|*****|
+// m == 1: |  |  |  |  |  |  |
+// m == 2: |--+--|--+--|--+--|
+// m == 3: |  |  |  |  |  |  |
+void print_column(int n,
+                  int m); // Print a single character, called by print_row
+// n: type of char in a single line
+// m: type of char in multiple lines
+// m == 0: |***** n is defined by the position in the line with particular m
+// m == 1: |  |
+// m == 2: |--+--
+// m == 3: |  |
+
+int main(void) {
+  // Initialize variables and read input
+  int row, col;
+  scanf("%d", &row);
+  scanf("%d", &col);
+
+  // The magic starts here
+  print_block(col, row);
+
+  return 0;
+}
+
+void print_block(int n, int m) {
+  for (int i = 0; i < m * 4; i++) {
+    print_row(n, i % 4);
+  }
+  print_row(n, 0); // The last line
+}
+
+void print_row(int n, int m) {
+  for (int i = 0; i < n * 6; i++) {
+    print_column(i % 6, m);
+  }
+  print_column(0, m); // The last char
+  printf("\n");
+}
+
+void print_column(int n, int m) {
+  if (n == 0) {
+    printf("|");
+  } else if (n == 1 || n == 2 || n == 4 || n == 5) {
+    if (m == 0) {
+      printf("*");
+    } else if (m == 2) {
+      printf("-");
+    } else {
+      printf(" ");
+    }
+  } else if (n == 3) {
+    if (m == 0) {
+      printf("*");
+    } else if (m == 2) {
+      printf("+");
+    } else {
+      printf("|");
+    }
+  }
+}