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')
})();