move exercises, lecture examples, labs into subfolders

Exercises/C7/ex3.c

@@ -0,0 +1,13 @@
+#include <stdio.h>
+#include <math.h>
+
+int main() {
+	float radius, height;
+
+	printf("Enter radius: ");
+	scanf("%f", &radius);
+	printf("Enter height: ");
+	scanf("%f", &height);
+
+	printf("Surface area: %f\n", 2*M_PI*radius*radius + 2*M_PI*radius*height);
+}