ATCGCGATCATCCATACTBEERCATKETCHUPTAG                       edit at 18
ATCGCGATCATCBEERCATKETCHUPACTBEERCATKETCHUPTAG            then 12
ATCGCGATBEERCATKETCHUPCBEERCATKETCHUPACTBEERCATKETCHUPTAG then 8
        ^^^^   vvvvvvv ^^^^   vvvvvvv   ^^^^   vvvvvvv