diff --git a/hello.c b/samples/hello.c
similarity index 100%
rename from hello.c
rename to samples/hello.c
diff --git a/samples/sample1.c b/samples/sample1.c
new file mode 100644
index 0000000..a6312a5
--- /dev/null
+++ b/samples/sample1.c
@@ -0,0 +1,52 @@
+/* prog 13-1,................. */
+
+double area(int),circumf(int);
+double volume(int),surface(int);
+int main(void)
+{
+   int r,item;
+
+   printf("(1) ...	(2) ...\n");
+   printf("(3) ....	(4) .....\n");
+   printf(".........:");
+   do
+      scanf("%d",&item);
+   while((item>4)||(item<1));
+   do
+   {
+      printf("....:");
+      scanf("%d",&r);
+   } while(r<=0);
+   printf("\n");
+   switch (item)
+   {
+      case 1:printf("..=%d,...=%.2f\n",r,area(r));
+             break;
+      case 2:printf("..=%d,...=%.2f\n",r,circumf(r));
+             break;
+      case 3:printf("..=%d,....=%.2f\n",r,volume(r));
+             break;
+      case 4:printf("..=%d,.....=%.2f\n",r,surface(r));
+   }
+   return 0;
+}
+ 
+double area(int r)	/* ....area()...... */
+{
+   return (PI*r*r);
+}
+ 
+double volume(int r)/* ....volume()....... */
+{
+   return (4/3*PI*r*r*r);
+}
+ 
+double surface(int r)/* ....surface()........ */
+{
+   return (4*PI*r*r);
+}
+ 
+double circumf(int r)/* ....circumf()...... */
+{
+   return (2*PI*r);
+}
diff --git a/samples/sample2.c b/samples/sample2.c
new file mode 100644
index 0000000..03971e7
--- /dev/null
+++ b/samples/sample2.c
@@ -0,0 +1,53 @@
+/* prog 13-1,................. */
+
+double area(int),circumf(int);
+double volume(int),surface(int);
+int main(void)
+{
+   int r,item;
+
+   printf("(1) ...	(2) ...\n");
+   printf("(3) ....	(4) .....\n");
+   printf(".........:");
+   do
+      scanf("%d",&item);
+   while((item>4)||(item<1));
+   do
+   {
+      printf("....:");
+      scanf("%d",&r);
+   } while(r<=:0);
+   printf("\n");
+   switch (item);
+   {
+      case 1:printf("..=%d,...=%.2f\n",r,area(r));
+             break;
+      case 2:printf("..=%d,...=%.2f\n",r,circumf(r));
+             break;
+      case 3:printf("..=%d,....=%.2f\n",r,volume(r));
+             break;
+      case 4:printf("..=%d,.....=%.2f\n",r,surface(r));
+   }
+   return 0;
+}
+ 
+double area(int r)	/* ....area()...... */
+{
+   return (PI*r*r);
+}
+ 
+double volume(int r)/* ....volume()....... */
+{
+   return (4/3*PI*r*r*r);
+}
+ 
+double surface(int r);/* ....surface()........ */
+{
+   return (4*PI*r*r);
+}
+ 
+double circumf(int r)/* ....circumf()...... */
+{
+   return (2*PI*r);
+}
+
diff --git a/samples/sample3.c b/samples/sample3.c
new file mode 100644
index 0000000..848acd2
--- /dev/null
+++ b/samples/sample3.c
@@ -0,0 +1,9 @@
+int main(void)
+{
+   int x=1;
+   int y=2;
+   int z=3;
+   x=y+z;
+}
+ 
+
diff --git a/samples/sample4.c b/samples/sample4.c
new file mode 100644
index 0000000..440e297
--- /dev/null
+++ b/samples/sample4.c
@@ -0,0 +1,9 @@
+int main(void)
+{
+   int x=1;
+   int y=2;
+   int z=3;
+   x=y+/z;
+}
+ 
+
diff --git a/samples/sample5.c b/samples/sample5.c
new file mode 100644
index 0000000..ac983fd
--- /dev/null
+++ b/samples/sample5.c
@@ -0,0 +1,8 @@
+int main(void)
+{
+   int x=1;
+   int y=2;
+   int z=3;
+   x=y+(-z;
+}
+
diff --git a/samples/sample6.c b/samples/sample6.c
new file mode 100644
index 0000000..10c946b
--- /dev/null
+++ b/samples/sample6.c
@@ -0,0 +1,8 @@
+int main(void)
+{
+   int x=1
+   int y=2;
+   int z=3;
+   x=y+z;
+}
+
diff --git a/samples/sample7.c b/samples/sample7.c
new file mode 100644
index 0000000..1d64adc
--- /dev/null
+++ b/samples/sample7.c
@@ -0,0 +1,7 @@
+int main(void)
+{
+   int x=1;
+   int y=2;
+   int z=3;
+   x=y+Z;
+