calc to anon

uses sysutils,math;
type
        TS=record
        s1,s2:string;
        end;
var
fl,k,i:longint;
n,n1,n2:extended;
ch:char;
s,s0:string;
ss:TS;

procedure help;
Begin
if fl=0 then begin
writeln('Format input:');
writeln('4+5');
writeln('5-9');
writeln('3*5.7');
writeln('8.0/7');
writeln('2^10');
writeln('sqrt 25');
writeln('cos 0.5');
writeln('sin 1');
write('>>> ');end
        else write('>>> ');
fl:=1;
End;

procedure vivod;
Begin
writeln(s0);
End;

procedure probel(ss:TS);
Begin
n:=strtofloat(ss.s2);
case ss.s1 of
        'sqrt':n:=(sqrt(n));
        'cos':n:=(cos(n));
        'sin':n:=(sin(n));
        end;
s0:=floattostr(n);
vivod;
End;

procedure raschot(ss:TS);
Begin
if ch=' ' then probel(ss)
        else
        begin
n1:=strtofloat(ss.s1);
n2:=strtofloat(ss.s2);
case ch of
        '+':n:=n1+n2;
        '-':n:=n1-n2;
        '*':n:=n1*n2;
        '/':n:=n1/n2;
        '^':n:=power(n1,n2);
        end;
s0:=floattostr(n);
vivod;
        end;
End;

function vvod:TS;
Begin
help;
readln(s);
if s='exit' then halt;
i:=0;ch:=#0;k:=0;
while i<length(s) do
        begin
        i:=i+1;
        if (s[i]='+')or(s[i]='-')or(s[i]='*')or(s[i]='/')or(s[i]='^')or(s[i]=' ')
                then begin ch:=s[i];k:=i;i:=length(s);end;
        end;
ss.s1:=copy(s,1,k-1);
ss.s2:=copy(s,k+1,length(s)-k);
vvod:=ss;
End;



BEGIN
while(true)do raschot(vvod);
END.