Ruby, программирование.

Валидация данных, при делении на ноль должно выдать ошибку. Как осуществить?

program
var
s: string;
a:array[1..4] of integer;
i:integer;
begin
 read(s);
 for i:=1 to 4 do a[i]:=0;
 
 for i:=0 to length(s) do
 begin
    if s[i]=')' then inc(a[1]);
    if s[i]='(' then inc(a[2]);
    if s[i]='!' then inc(a[3]);
    if s[i]='.' then inc(a[4]);
 end;
 
 if(a[1]>a[2])and(a[1]>a[3])and(a[1]>a[4]) then write('Funny')else
 if(a[2]>a[1])and(a[2]>a[3])and(a[2]>a[4]) then write('Sad') else
 if(a[3]>a[2])and(a[3]>a[1])and(a[3]>a[4]) then write('Angry') else
 if(a[4]>a[2])and(a[4]>a[3])and(a[4]>a[1]) then write('Deep') else
    write('Unclear');

end.

program
var
s: string;
a:array[1..4] of integer;
i:integer;
begin
 read(s);
 for i:=1 to 4 do a[i]:=0;
 
 for i:=0 to length(s) do
 begin
    if s[i]=')' then inc(a[1]);
    if s[i]='(' then inc(a[2]);
    if s[i]='!' then inc(a[3]);
    if s[i]='.' then inc(a[4]);
 end;
 
 if(a[1]>a[2])and(a[1]>a[3])and(a[1]>a[4]) then write('Funny')else
 if(a[2]>a[1])and(a[2]>a[3])and(a[2]>a[4]) then write('Sad') else
 if(a[3]>a[2])and(a[3]>a[1])and(a[3]>a[4]) then write('Angry') else
 if(a[4]>a[2])and(a[4]>a[3])and(a[4]>a[1]) then write('Deep') else
    write('Unclear');

end.