Error: Incompatible Types: Got

var a,b,d,c,r,n : integer;

BEGIN
writeln(‘vuvedi 4islo’); readln(a);
writeln(‘vuvedi 4islo’); readln(b);
writeln(‘vuvedi 4islo’); readln(c);
n:=(a*a)-(4*b*c);
r:=(-b+sqrt(n))/(2*a);
d:=(-b-sqrt(n))/(2*a);
writeln(‘rezultata e ‘, r , d);
readln;
END.

that is on pascal and here are the errors:

9 / 19 untitl~1.pas
Error: Incompatible types: got “S80REAL” expected “LONGINT”
10 / 19 untitl~1.pas
Error: Incompatible types: got “S80REAL” expected “LONGINT”
14 untitl~1.pas
Fatal: There were 2 errors compiling module, stopping