Elevator Trouble

#include <bits/stdc++.h>

using namespace std;

static inline double func(double x)
{
    return exp(x) + sqrt(x);
}

int main() {
    cin.sync_with_stdio(false);
    int floors, start, goal, u, d;
    cin >> floors >> start >> goal >> u >> d;

    queue<pair<int, int>> to_visit;
    int shortest = -1;

    to_visit.push(make_pair(start, 0));

    const int MAX_LEVELS = 25;

    while (shortest == -1) {
        auto elem = to_visit.front();
        to_visit.pop();
        if (elem.first == goal) {
            shortest = elem.second + 1;
            break;
        }

        if (elem.second == MAX_LEVELS) {
            break;
        }

        if (elem.first < 1 || elem.first > floors) {
            continue;
        }

        to_visit.push(make_pair(elem.first + u, elem.second + 1));
        to_visit.push(make_pair(elem.first + d, elem.second + 1));
    }

    if (shortest == -1) {
        cout << "use the stairs\n";
    } else  {
        cout << shortest << "\n";
    }

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: RUNTIME ERROR

Test 3

Verdict: RUNTIME ERROR

Test 4

Verdict: RUNTIME ERROR

Test 5

Verdict: RUNTIME ERROR

Test 6

Verdict: RUNTIME ERROR

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: RUNTIME ERROR

Test 9

Verdict: RUNTIME ERROR

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: RUNTIME ERROR

Test 12

Verdict: RUNTIME ERROR