writeln "a) : ",  
(2 + 3)**2;         
writeln "b) : ", 
5/7;
writeln "c) : ",
5/7 = 0.714;
writeln "d) : ",
5 div 7;
writeln "e) : ",
5 mod 7;
writeln "f) : ",
2/0;
writeln "g) : ",
x * y;                   
writeln "h) : ",
2 * (3+1)  > 4;
writeln "i) : ",
forall n in [0 .. 100] | n mod 10 /= 9;
writeln "j) : ",
exists n in [0 .. 100] | n mod 10 /= 9;
writeln "k) : ", 
y div 10 = 9;
writeln "m) : ", 
4;
writeln "n) : ",
"abc" < "abd";