#include <bits/stdc++.h>

using namespace std;

typedef unsigned u32;

u32 count(u32 n) {
  if (n < 2) {
    return 0;
  }
  u32 v = sqrt(n);
  vector<u32> scnt(v + 1), lcnt(v + 1);
  for (u32 i = 1; i <= v; ++i) {
    scnt[i] = i - 1;
  }
  for (u32 i = 1; i <= v; ++i) {
    lcnt[i] = n / i - 1;
  }
  assert(lcnt[1] == n - 1);
  for (u32 p = 2; p <= v; ++p) {
    if (scnt[p] == scnt[p - 1]) {
      continue;
    }
    u32 q = p * p, c = scnt[p - 1];
    u32 w = v / p, e = min(v, n / q), m = n / p;
    for (u32 i = 1; i <= w; ++i) {
      lcnt[i] -= lcnt[i * p] - c;
    }
    for (u32 i = w + 1; i <= e; ++i) {
      lcnt[i] -= scnt[m / i] - c;
    }
    for (u32 i = v; i >= q; --i) {
      scnt[i] -= scnt[i / p] - c;
    }
  }
  u32 ret = scnt[cbrt(n)];
  for (u32 i = 2; i <= v; ++i) {
    if (scnt[i] != scnt[i - 1]) {
      ret += lcnt[i] - scnt[i];
    }
  }
  return ret;
}

int main() {
  u32 n;
  scanf("%u", &n);
  u32 lo = 1, hi = 5150000, ans = 0;
  while (lo <= hi) {
    u32 mi = (lo + hi) >> 1;
    if (count(mi) < n) {
      lo = mi + 1;
    } else {
      ans = mi;
      hi = mi - 1;
    }
  }
  printf("%d\n", ans);
  return 0;
}