var a:array[1..1000]of integer;
n,i,j,dem,m1,m2,m3:integer;
b:boolean;
begin
readln(n);
for i:=1 to n do
readln(a[i]);
m1:=0;m2:=0;m3:=0;dem:=0;
for i:=1 to n do begin
b:=true;
for j:=2 to a[i]-1 do
if (a[i] mod j=0)or(a[i]<=1) then begin b:=false; break; end;
if b then ;
if abs(a[i]-a[i+1])<m1 then beign m1:=abs(a[i]-a[i+1]); m2:=a[i]; m3:=a[i+1]; end;
end;
writeln('co ',dem,' so nguyen to');
writeln(m2,' va ',m3,' co khoang cach lon nhat');
writeln('cac phan tu la phan tu chinh giua');
for i:=1 to n do begin
m2:=0;m3:=0;
for j:=1 to n do
if a[i]>a[j] then m2:=m2+1 else if a[i]<a[j] then m3:=m3+1;
if m2=m3 then writeln('phan tu thu ',i);
end;
readln;
end.