move exercises, lecture examples, labs into subfolders

Exercises/C5/ex4.c

@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <math.h>
+
+int main() {
+	float r;
+	printf("Enter radius: ");
+	scanf("%f", &r);
+
+	printf("Area of sphere: %f\n", 4.0*M_PI*r*r);
+	printf("Volume of sphere: %f\n", M_PI*r*r*r*4.0/3.0);
+}