дальше измени сама

var month:integer;
begin
readln(month);
if ((month >0 ) and ( month < 13)) then
case month of
1 : writeln ('january (31 days) ');
2 : writeln ('fabruary (28 days) ');
3 : writeln ('march (31 days)');
4 : writeln ('April (31 days) ');
5 : writeln ('fabruary (28 days)');
6 : writeln ('march (31 days)');
7 : writeln ('january (31 days) ');
8 : writeln ('fabruary (28 days) ');
9 : writeln ('march (31 days)');
10 : writeln ('january (31 days) ');
11 : writeln ('fabruary (28 days) ');
12: writeln ('march (31 days)');
end
else writeln('error');
readln;
end.