function y=dprinos(x)
%y=dprinos(x)

n=5;
c(1)=10000;
c(2)=15000;
c(3)=12000;
c(4)=15000;
c(5)=7000;
y=0;
for i=1:n
   y=y-i*c(i)/(1+x)^(i+1);
end
