shell programming

[zy413952631]

please help me check the script below and tell me what is wrong and how to correct.Thank you

read num
for i in 1 2 3
s =`echo $num |cut -c $i `

[gpraghuram]

for i in 1 2 3 
do #missing
s =`echo $num |cut -c $i ` 
done #missing

also what is $num value?

Raghu