2002+2003*2001/(2002*2003-1)
=[2002+(2002+1)*2001]/[2002*(2002+1)-1]
=[2002+2002*2001+2001]/[2002*2002+2002-1]
=[2002*(1+2001)+2001]/[2002*2002+2001]
=[2002*2002+2001]/[2002*2002+2001]
=1
2002+2003*2001/(2002*2003-1)
=[2002+(2002+1)*2001]/[2002*(2002+1)-1]
=[2002+2002*2001+2001]/[2002*2002+2002-1]
=[2002*(1+2001)+2001]/[2002*2002+2001]
=[2002*2002+2001]/[2002*2002+2001]
=1