diff --git a/labs/04/Makefile b/labs/04/Makefile
new file mode 100644
index 0000000..66bdd94
--- /dev/null
+++ b/labs/04/Makefile
@@ -0,0 +1,30 @@
+LDFLAGS = -L/opt/homebrew/opt/flex/lib
+CPPFLAGS = -I/opt/homebrew/opt/flex/include
+
+# generate 
+example: code_generator.py 
+	python3 code_generator.py > example.ac
+
+# compile 
+gen_lex:
+	lex language_ac.l
+	gcc $(CPPFLAGS) $(LDFLAGS) lex.yy.c -o lexical_scan -lfl
+
+test: example.ac
+	./lexical_scan < example.ac
+# run lex, then compile lex.yy.c then run lexical_scan
+#
+stress:
+	lex language_ac.l
+	gcc $(CPPFLAGS) $(LDFLAGS) lex.yy.c -o lexical_scan -lfl
+	python3 code_generator.py --stress
+	./lexical_scan < random_code.ac
+run:
+	lex language_ac.l
+	gcc $(CPPFLAGS) $(LDFLAGS) lex.yy.c -o lexical_scan -lfl
+	python3 code_generator.py > example.ac
+	./lexical_scan < example.ac
+
+# Limpiar archivos generados
+clean:
+	rm -f lex.yy.c lexical_scan example.ac
diff --git a/labs/04/code_generator.py b/labs/04/code_generator.py
new file mode 100644
index 0000000..4ae97e1
--- /dev/null
+++ b/labs/04/code_generator.py
@@ -0,0 +1,78 @@
+import string
+import random
+import argparse
+
+def id_generator(size=10, chars=string.ascii_uppercase + string.digits):
+    return ''.join(random.choice(chars) for _ in range(size))
+
+opreators = ["+","-","*","/"]
+
+def get_comment_line():
+    comment_line = "//%s" % (id_generator())
+    return comment_line
+
+def get_float_line():
+    float_line = "f %s" % (random.choice(string.ascii_lowercase))
+    return float_line
+
+def get_integer_line():
+    integer_line = "i %s"% (random.choice(string.ascii_lowercase))
+    return integer_line
+
+def get_asigment_line():
+    asigment_line = "%s = %s" %(random.choice(string.ascii_lowercase),\
+        random.randint(0,100))
+    return asigment_line
+
+def get_asigment_line_2():
+    asigment_line_2 = "%s = %s %s %s" % \
+            (random.choice(string.ascii_lowercase),\
+            random.choice(string.ascii_lowercase),\
+            random.choice(opreators),\
+            random.randint(0,100))
+    return asigment_line_2
+
+def get_print_line():
+    print_line = "p %s" % (random.choice(string.ascii_lowercase))
+    return print_line
+
+
+parser = argparse.ArgumentParser(description='Generate random AC code')
+parser.add_argument('--stress', dest='stress', action='store_true',\
+        help='generate HUGE code to stress the lab')
+args = parser.parse_args()
+
+if args.stress:
+    f= open("random_code.ac","w+")
+    for x in range(0, 100000):
+        comment_line = get_comment_line()
+        float_line = get_float_line()
+        integer_line = get_integer_line()
+        asigment_line = get_asigment_line()
+        asigment_line_2 = get_asigment_line_2()
+        print_line = get_print_line()
+
+        f.write(comment_line + "\n")
+        f.write(float_line + "\n")
+        f.write(integer_line + "\n")
+        f.write(asigment_line+ "\n")
+        f.write(asigment_line_2 + "\n")
+        f.write(print_line + "\n")
+
+    f.close()
+
+else:
+    comment_line = get_comment_line()
+    float_line = get_float_line()
+    integer_line = get_integer_line()
+    asigment_line = get_asigment_line()
+    asigment_line_2 = get_asigment_line_2()
+    print_line = get_print_line()
+
+    print(comment_line)
+    print(float_line)
+    print(integer_line)
+    print(asigment_line)
+    print(asigment_line_2)
+    print(print_line)
+
diff --git a/labs/04/example.ac b/labs/04/example.ac
new file mode 100644
index 0000000..ab2f9f6
--- /dev/null
+++ b/labs/04/example.ac
@@ -0,0 +1,6 @@
+//OFKZ5W996B
+f q
+i q
+r = 61
+o4 = f - 98
+p k
diff --git a/labs/04/language_ac.l b/labs/04/language_ac.l
new file mode 100644
index 0000000..fc39afe
--- /dev/null
+++ b/labs/04/language_ac.l
@@ -0,0 +1,30 @@
+%{
+#include <stdio.h>
+%}
+
+%option noyywrap
+
+letter [a-eg-hj-oq-zA-EG-HJ-OQ-Z]
+digit [0-9]
+number {digit}+
+
+%%
+\/{2}.*                 { printf("COMMENT "); }
+f                       { printf("floatdcl "); }
+i                       { printf("intdcl "); }
+=                       { printf("assign "); }
+\+                      { printf("plus "); }
+\-                      { printf("minus "); }
+\*                      { printf("multiplication "); }
+\/                      { printf("division "); }
+p                      { printf("print "); }
+({letter}{digit}*)+      { printf("id "); }
+(0|([1-9]{digit}*))\.(({digit}*[1-9])|0)   { printf("fnum "); }
+{number}                  { printf("inum "); }
+[ \t]+                  /* ignore whitespace */
+%%
+
+int main() {
+    yylex();
+    return 0;
+}
diff --git a/labs/04/lexical_scan b/labs/04/lexical_scan
new file mode 100755
index 0000000..1a20455
Binary files /dev/null and b/labs/04/lexical_scan differ