declare var require: any;
let lines: string[] = require("fs").readFileSync("/dev/stdin", "utf8").split("\n");
let p = lines[1].split(' ').map(Number);

const getMinIndex = (arr: number[]) => arr.reduce((acc, cur, i) => acc.min > i ? {min: i, i} : acc, {min: Infinity, i: -1});

const q = [];
while(p.length > 0) {
	const mins = getMinIndex(p.slice(0, -1));
	q.push(p[mins.i], p[mins.i+1]);
}
console.log(q.join(' '))