diff --git a/labs/03/Practica3.l b/labs/03/Practica3.l
new file mode 100644
index 0000000..5cefa61
--- /dev/null
+++ b/labs/03/Practica3.l
@@ -0,0 +1,25 @@
+%{
+#include "y.tab.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+%}
+
+%{
+int line_number = 1;
+%}
+
+%%
+
+a|the                    {yylval.sval = strdup(yytext); return ARTICLE;}
+boy|girl|flower          {yylval.sval = strdup(yytext); return NOUN;}
+touches|likes|sees       {yylval.sval = strdup(yytext); return VERB;}
+with                     {yylval.sval = strdup(yytext); return PREP;}
+
+[ \t]+                   /* ignore whitespace */
+^[ \t]*\n                /* ignore blank lines */
+
+\n                       { line_number++; return '\n'; }
+
+
+%%
diff --git a/labs/03/Practica3.y b/labs/03/Practica3.y
new file mode 100644
index 0000000..b95aef8
--- /dev/null
+++ b/labs/03/Practica3.y
@@ -0,0 +1,63 @@
+%{
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+extern int line_number;
+extern FILE *yyin;
+extern int yylex();
+void yyerror(const char *s);
+%}
+
+%union {
+    char *sval;
+}
+
+%token <sval> ARTICLE NOUN VERB PREP
+
+%%
+
+start: sentences '\n' { printf("PASS\n"); }
+
+
+sentences: /* empty */
+          | sentences sentence '\n'
+
+sentence: NOUN_PHRASE VERB_PHRASE { printf("PASS\n"); }
+        | NOUN_PHRASE { printf("PASS\n"); }
+        | VERB_PHRASE { printf("PASS\n"); }
+
+NOUN_PHRASE: ARTICLE NOUN
+           | ARTICLE NOUN PREP_PHRASE
+;
+
+VERB_PHRASE: VERB
+           | VERB NOUN_PHRASE
+;
+
+PREP_PHRASE: PREP NOUN_PHRASE
+;
+
+
+%%
+
+void yyerror(const char *s) {
+    fprintf(stderr, "FAIL... FIN DE ARCHIVO\n");
+}
+
+int main(int argc, char **argv) {
+    if (argc == 2) {
+        if (!(yyin = fopen(argv[1], "r"))) {
+            perror("Error al abrir el archivo: ");
+            return 1;
+        }
+
+        yyparse();
+        fclose(yyin);
+        
+    } else {
+        fprintf(stderr, "Usage: %s filename\n", argv[0]);
+        return 1;
+    }
+
+    return 0;
+}