// 设置标准输入接口
const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;
void (async function () {
const arr = (await readline()).split(" ").map(Number);
const map = {};
arr.forEach((element) => {
map[element] = (map[element] || 0) + 1;
});
let res = 0;
Object.entries(map).forEach(([key, val]) => {
res += Math.ceil(val / (key + 1)) * (Number(key) + 1);
});
console.log(res);
})();