PROGRAM Bai_tap;
USES CRT;
Var A:array[1..100] of integer; i,cs,n:integer;
kt:boolean; BEGIN Clrscr; Write('Nhap so luong phan tu cua day : ');
Readln(n);
For i:=1 to n do Begin Write('Nhap phan tu thu ',i,' : ');
Readln(A[i]);
End;
kt:=True; cs:=A[2]-A[1]; For i:=3 to n do If (A[i]-A[i-1]) <> cs then Begin kt:=False;
Break;
End;
If kt=True then Writeln('Day A la mot cap so cong!') Else Writeln('Day A khong phai la mot cap so cong!'); READLN;
END.