program sum;
{$APPTYPE CONSOLE}
uses SysUtils;
var a, b, c, d: real;
begin
    write('Please Enter a: ');
    readln(a);
    write('Please Enter b: ');
    readln(b);
    write('Please Enter c: ');
    readln(c);
    if ( a = 0 ) and ( b = 0 ) then begin
        writeln('a=0 and b=0!' );
    end 
    else begin
        d :=  abs( c ) / sqrt( a * a + b * b );
        writeln('d =', d:8:3 );
    end; 
    readln
end.