nTh root of a number

// I can't tell you what it really is,
// I can only tell you what it feels like.
#include "bits/stdc++.h"
using namespace std;
#define int long long
#define ld long double

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int A, N;
  cin >> A >> N;
  ld ans = -1, lo = 1, hi = 20;
  const ld inf = 1e-14;
  const ld preLog = log(A);
  // cout << preLog << '\n';
  while (!(hi-lo<=inf)) {
    ld mid = (lo+hi)/2.0;
    // cout << N*log(mid) << ' ' << preLog << '\n';
    if (preLog-N*log(mid) >= inf) {
      lo = mid + inf;
      ans = mid;
    }
    else hi = mid - inf;
  }
  cout << fixed << setprecision(10) << ans;
  return 0;
}
// 1). Try forming/rearranging the equations if any
// 2). If problem asks to count, try counting in reverse(it can be easier sometimes)