diff --git a/labs/04/lex_analaizer.l b/labs/04/lex_analaizer.l
new file mode 100644
index 0000000..08ab2bd
--- /dev/null
+++ b/labs/04/lex_analaizer.l
@@ -0,0 +1,36 @@
+%{
+#include <stdio.h>
+int yywrap(void) { return 1; }
+%}
+
+%%
+
+"//".*              printf("COMMENT");
+f                   printf("floatdcl ");
+i                   printf("intdcl ");
+p                   printf("print ");
+[a-eg-hj-oq-z]      printf("id ");
+[0-9]+              printf("inum ");
+[0-9]*\.[0-9]+      printf("fnum ");
+=                   printf("assign ");
+\+                  printf("plus ");
+\-                  printf("substraction\n");
+\*                  printf("multiplication\n");
+\/                  printf("division\n");
+[ \t]+              /* ignore spaces */
+\n                  printf("\n");
+
+%%
+
+int main(int argc, char **argv) {
+    if (argc > 1) {
+        FILE *fp = fopen(argv[1], "r");
+        if (!fp) {
+            perror("File open failed");
+            return 1;
+        }
+        yyin = fp;
+    }
+    yylex();
+    return 0;
+}
\ No newline at end of file