diff --git a/sk1/compressor.c b/sk1/compressor.c
index e69de29..aff0f25 100644
--- a/sk1/compressor.c
+++ b/sk1/compressor.c
@@ -0,0 +1,4 @@
+int compress_1(const char* input_file_name, const char* output_file_name);
+int decompress_1(const char* input_file_name, const char* output_file_name);
+int compress_2(const char* input_file_name, const char* output_file_name);
+int decompress_2(const char* input_file_name, const char* output_file_name);
\ No newline at end of file