txt = "Try Lua before downloading it. Enter your Lua program or choose one of the demo programs below.";

function Count_Substring(s1, s2)
return select(2, s1:gsub( s2, ""))
end
t = {};

for word in string.gmatch(txt , "%a+") do
table.insert(t, tonumber(Count_Substring(txt , word)), word);
-- print(word);
-- print(Count_Substring(txt , word));
end

-- for i,n in ipairs(t) do print(n) end
-- print(table.maxn(t));
print(t[table.maxn(t)]);