const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;
void (async function () {
// Write your code here
let line = Number(await readline());
let arr = [];
let obj = {
insert: (a, b) => {
if (arr.indexOf(a) === -1) {
arr.push(b);
} else {
arr.splice(arr.indexOf(a), 0, b);
}
},
delete: (a) => {
if (arr.indexOf(a) !== -1) {
arr.splice(arr.indexOf(a), 1);
}
},
};
for (let i = 0; i < line; i++) {
let sk = (await readline()).split(" ");
let type = sk[0];
sk.shift();
obj[type](...sk);
}
console.log(arr.join(' ')||'NULL')
})();