diff --git a/guoyi.run b/guoyi.run
index 50b4e1c..17214a2 100644
--- a/guoyi.run
+++ b/guoyi.run
@@ -15,6 +15,8 @@ if ( (argnumber == 0) || (argnumber >7) )
 |        === Parameters     Details ===              |
 |        ==============================              |
 |        filename type weight K cons resamp prefix   |
+|          - filename extension must be lower case   |
+|            fas/fasta tnt/ss are allowed            |
 |          - type should be 32, dna, prot, num       |
 |            num=number, dna=DNA, prot=protein       |
 |            32=max number allowed (default)         |
@@ -44,16 +46,31 @@ var:
   dostr domjr dohlf contype
   doew doiw doeiw dowt wtstring wttype
   kvalue
-  search;
+  search
+  isfas istnt input;
 
 set dojak 0; set doboot 0; set dosym 0; set dobrs 0; set dorbrs 0; set rsmp 0; set dobremer 0;
 set dostr 0; set domjr 0; set dohlf 0;
 set doew 0; set doiw 0; set doeiw 0; set dowt 0; set wttype 0;
 set kvalue 12;
 set search 0;
+set isfas 0; set istnt 0;
 
 goto=%0;
 
+/*Get prefix and extension of input*/
+set input $%1;
+
+/*confirm input format*/
+if ((eqstring [ $input>. fas ]) || (eqstring [ $input>. fasta ]))
+  set isfas 1;
+else
+if ((eqstring [ $input>. tnt ]) || (eqstring [ $input>. ss ]))
+  set istnt 1;
+else
+  errmsg extension name of input file must be fas/fasta (for fas format) or tnt/ss (for Hennig86/NONA/TNT format);
+end end
+
 /*handle weighting type*/
 if (argnumber>=3)
   set wtstring $%3;
@@ -185,7 +202,12 @@ if ('dowt')
 end
 
 /*Reopen tnt*/
-procedure %1;
+if ('istnt')
+  procedure $input;
+else
+if ('isfas')
+  procedure & $input;
+end end
 hold 10000;
 
 /*handle search*/