const
m=300;
var i:byte;
a,b,s:integer;
begin
b:=0;s:=0;
for i:=1 to 12 do
begin
read(a);
if a>m+b then
begin
writeln(-i);
exit;
end;
if m+b-a>=100
then
begin
s:=s+100*((m+b-a) div 100);
b:=(m+b-a)mod 100;
end
else b:=m+b-a;
end;
writeln(1.2*s+b:0:0);
end.