uses crt;
var
a:array [1..4] of integer;
b:array [1..3] of integer;
c,d,i:integer;
g:char;
begin
clrscr;
for i:=1 to 4 do
readln (a[i]);
for i:=1 to 4 do
begin
c:=a[i];
if a[i]>c then c:=a[i]
end;
for i:=1 to 3 do
readln (b[i]);
for i:=1 to 3 do
begin
d:=b[i];
if b[i]<d then d:=b[i]
end;
if c>d then g:=chr(d) else g:=chr(c);
writeln (g);
end.