function [atil b]=contorno3(nv,nc,a,n,m,conec,R)
atil=a;
b=zeros(nv,1);
aux=zeros(nv);
for i=1:n
  for j=1:m
    if ((j==1 || j==n) )
          k=(j-1)*n + i;
          atil(k,:)=0;
          atil(k,k)=1;
          if (j==n) b(k)=100; end
    end
    if ((abs(i-30)<20) && (abs(j-30)<10))
          k=(j-1)*n+i;
          aux(k)=1;
    end
  end   
end
for k=1:nc
   n1=conec(k,1);
   n2=conec(k,2);
   if (aux(n1)+aux(n2)>0)
     R(k)=0.01;
   end
end
return
end