Problem p02690 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <string>
#include <vector>

#define rep(i, n) for (int(i) = 0; (i) < (n); (i)++)
#define rep2(i, a, b) for (int(i) = a; (i) < (b); (i)++)
#define all(x) (x).begin(), (x).end()

using namespace std;
using ll = long long int;

const int inf = 1001001000;
const long long int Inf = 1001001001001001000;

void print(vector<vector<int>> a) {
  for (int i = 0; i < a.size(); i++) {
    for (int j = 0; j < a[i].size(); j++) {
      cout << a[i][j] << " ";
    }
    cout << endl;
  }
}

void print(vector<vector<long long int>> a) {
  for (int i = 0; i < a.size(); i++) {
    for (int j = 0; j < a[i].size(); j++) {
      cout << a[i][j] << " ";
    }
    cout << endl;
  }
}

void print(vector<int> a) {
  int n = a.size();
  for (int j = 0; j < n; j++) {
    if (j != n - 1)
      cout << a[j] << " ";
    else
      cout << a[j] << endl;
  }
}

void print(vector<long long int> a) {
  int n = a.size();
  for (int j = 0; j < n; j++) {
    if (j != n - 1)
      cout << a[j] << " ";
    else
      cout << a[j] << endl;
  }
}

void print(set<int> a) {
  for (auto x : a)
    cout << x << " ";
  cout << endl;
}

// 繰り返し2乗法を用いたべき乗.x^nを返す.
long long int pow_(long long int x, long long int n) {
  long long int res = 1;
  while (n) {
    if (n & 1) {
      res *= x;
    }
    n >>= 1;
    x = x * x;
  }
  return res;
}

int main() {
  ll x;
  cin >> x;
  int y = 1000;
  for (ll a = -y; a < y; a++) {
    for (ll b = -y; b < y; b++) {
      if (a * a * a * a * a - b * b * b * b * b == x) {
        cout << a << " " << b << endl;
        return 0;
      }
    }
  }
  assert(false);

  return 0;
}

Error: WA

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <string>
#include <vector>

#define rep(i, n) for (int(i) = 0; (i) < (n); (i)++)
#define rep2(i, a, b) for (int(i) = a; (i) < (b); (i)++)
#define all(x) (x).begin(), (x).end()

using namespace std;
using ll = long long int;

const int inf = 1001001000;
const long long int Inf = 1001001001001001000;

void print(vector<vector<int>> a) {
  for (int i = 0; i < a.size(); i++) {
    for (int j = 0; j < a[i].size(); j++) {
      cout << a[i][j] << " ";
    }
    cout << endl;
  }
}

void print(vector<vector<long long int>> a) {
  for (int i = 0; i < a.size(); i++) {
    for (int j = 0; j < a[i].size(); j++) {
      cout << a[i][j] << " ";
    }
    cout << endl;
  }
}

void print(vector<int> a) {
  int n = a.size();
  for (int j = 0; j < n; j++) {
    if (j != n - 1)
      cout << a[j] << " ";
    else
      cout << a[j] << endl;
  }
}

void print(vector<long long int> a) {
  int n = a.size();
  for (int j = 0; j < n; j++) {
    if (j != n - 1)
      cout << a[j] << " ";
    else
      cout << a[j] << endl;
  }
}

void print(set<int> a) {
  for (auto x : a)
    cout << x << " ";
  cout << endl;
}

// 繰り返し2乗法を用いたべき乗.x^nを返す.
long long int pow_(long long int x, long long int n) {
  long long int res = 1;
  while (n) {
    if (n & 1) {
      res *= x;
    }
    n >>= 1;
    x = x * x;
  }
  return res;
}

int main() {
  ll x;
  cin >> x;
  for (ll a = -70; a < 70; a++) {
    for (ll b = -70; b < 70; b++) {
      if (a * a * a * a * a - b * b * b * b * b == x) {
        cout << a << " " << b << endl;
        return 0;
      }
    }
  }
  assert(false);

  return 0;
}