when i am executing the following code i m getting IndexError:list out of range

Code:
import os;
import sys;
file1=open(sys.argv[1],"r").readlines() # 1_train.txt
file2=open(sys.argv[2],"w")
for i in range(0, len(file1)):
	w=file1[i].split();
 	if(len(w)==3):
		file2.write(w[0]+"_"+w[2]+"\t"+w[1]+"\n");
	else:
		file2.write("\n&quo
...