Odd Topic

Animesh the Cryptographer loves $Odd$ things. He taught his two friends Mukul and Suman some topics on cryptography. He taught Mukul for $n$ days and Suman for $m$ days. He taught $a$i topic to Mukul on $i$th day and $b$j topic to Suman on $j$th day. Animesh decided to conduct test on such topics which was taught odd number of times after merging all the topics taught to Mukul from day $l$1 to $r