Program TB_Cong_4_So;
uses crt;
Var s,a: real;
Begin
     Clrscr;
     S:=0;
     Write('Nhap so thu nhat:');readln(a); S:=S+a;
     Write('Nhap so thu hai:');readln(a); S:= S+a;
     Write('Nhap so thu ba:');readln(a); S:=S+a;
     Write('Nhap so thu tu:');readln(a); S:=S+a;
     Writeln('Trung binh cong: ',S/4:10:2);
     readln