var a,b:aray[1..10] of byte;
n1,n2,n3,ni,x:byte;
f1,f2:text;
begin
assign(f1,'sn.dat');
while not eof (f1) do
begin
readln(f,A[ni]);
write(A[ni]);
end;
close(f1)
n1:=1;
n2:=2;n3:=3;
begin
x:=ni
if x=1 then write(f,'snsx.dat')
if x=2 then assign(f2,'sn.dat');
rewite(f2);
write(A[n2]);
readln...