diff --git a/cv1/program.c b/cv1/program.c
index 8b13789..c7666a1 100644
--- a/cv1/program.c
+++ b/cv1/program.c
@@ -1 +1,16 @@
+#include <stdio.h>
 
+
+int main()
+{
+    char c;
+    while ((c = getchar()) != EOF) {
+        if(c<='z'&&c>='a'){
+            c=c+('A'-'a');
+        }else if(c<='Z'&&c>='A'){
+            c=c-('A'-'a');
+        }
+        printf("%c",c);
+    }
+    return 0;
+}