diff --git a/sk4/program.c b/sk4/program.c
index 2f53ec5..ead3aca 100644
--- a/sk4/program.c
+++ b/sk4/program.c
@@ -5,28 +5,34 @@
 unsigned char tape[30000] = {0};
 unsigned char* ptr = tape;
 
+typedef enum {
+INK,           DEK,
+BREK,          GLEK,
+BF_NEXT,       BF_PREV,
+BF_LOOP_START, BF_LOOP_END,
+} brainfuck_instruction_t;
+
 void interpret(char* input) {
     char current_char;
     size_t i;
     size_t loop;
-    size a;
     for (i = 0; input[i] != 0; i++) {
         current_char = input[i];
-        if (current_char == 'TUK') {//
+        if (current_char == 'INK') {// >
             ++ptr;
-        } else if (current_char == 'FUK') {//
+        } else if (current_char == 'DEK') {// <
             --ptr;
-        } else if (current_char == 'INK') {//+
+        } else if (current_char == 'BREK') {// +
             ++*ptr;
-        } else if (current_char == 'DEK') {//-
+        } else if (current_char == 'GLEK') {// -
             --*ptr;
-        } else if (current_char == 'PUK' ) {//.
+        } else if (current_char == 'PUK' ) {// .
             putchar(*ptr);
-        } else if (current_char == 'KUK') {//,
+        } else if (current_char == 'KUK') {// ,
             *ptr = getchar();
-        } else if (current_char == '[') {//
+        } else if (current_char == '[') {//start loop
             continue;
-        } else if (current_char == ']' && *ptr) {//
+        } else if (current_char == ']' && *ptr) {//stop loop
             loop = 1;
             while (loop > 0) {
                 current_char = input[--i];
diff --git a/sk4/program.exe b/sk4/program.exe
index 47aa69b..28b5d48 100644
Binary files a/sk4/program.exe and b/sk4/program.exe differ