let j,u,k,e,r="overflow",read_line,int_of_string,print_endline,String.length;;let g s=let n=r s in let rec($)i a=if i=n then a else(i+1)$(s.[i]::a)in 0$[]and h c=Char.code c-48;;let(&)v w=let f x=if x<=9then(x,0)else(x mod 10,1)in let rec(^)o=function|([],[],1)->1::o|([],[],_)->o|(a::b,[],z)->let s,t=f(h a+z)in(s::o)^(b,[],t)|([],c::d,z)->let s,t=f(h c+z)in(s::o)^([],d,t)|(a::b,c::d,z)->let s,t=f(h a+h c+z)in(s::o)^(b,d,t)in[]^(g v,g w,0);;let n=read_int();;let rec f i=if i<n then(let x=u()and y=u()in let s=r x and t=r y in if s>80||t>80then e j else if s<10&&t<10then Printf.printf"%d
"(k x+k y)else(let z=x&y in if List.length z>80then e j else(List.iter(fun e->print_int e)z;print_newline()));f(i+1));;f 0