End;kt:=true;If N>2 thenBegind:=a[1]-a[2];i:=2;
While (i<N)and(a[i]-a[i+1]=d) do inc(i);If i<>N then kt:=false;End;If kt then Write('Day a1,...,a',N,'
lap thanh 1 cap so cong')Else Write('Day a1,...,a',N,' khong
lap thanh 1 cap so cong');Readln;END9. P[r]