diff --git a/du1 b/du1
new file mode 100644
index 0000000..447c1a5
--- /dev/null
+++ b/du1
@@ -0,0 +1,31 @@
+#include <assert.h>
+#include <ctype.h>
+#include <stdio.h>
+#include <assert.h>
+#include <string.h>
+
+int main (){
+  int c;
+  int counter;
+  counter=0;
+  c=getchar();
+  while (1==1){
+      if (c=='\n')
+        counter=counter+1;
+      if (c==EOF){
+        return -1;
+      }
+    if ('a' <= c && c <= 'z') {
+        putchar(toupper (c));
+        printf("\nPočet riadkov: %d\n",counter);
+        break;
+  } else{
+        putchar(tolower (c));
+        printf("\nPočet riadkov: %d\n",counter);
+        break;
+    }
+    
+    putchar (c);
+  assert (! ferror (stdin));
+  return 0;
+  }
\ No newline at end of file