function Ir=dekoder7_4(r)
R=r;
s1=rem(r(1)+r(3)+r(5)+r(7),2);
s2=rem(r(2)+r(3)+r(6)+r(7),2);
s3=rem(r(4)+r(5)+r(6)+r(7),2);

s=s1*2^0+s2*2^1+s3*2^2;
if s~=0
    R(s)=rem(r(s)+1,2);
end
Ir=[R(3) R(5) R(6) R(7)];