divmgl

function solution(A) {
  var L = A.length; // Length of the array
  var X = ((L + 1) * L) / 2; // Sum from 1..L
  var Y = 0; // Sum of evaluated values
  var I = 0; // Counter
  var F = []; // Found elements
  var V = -1; // Container
    
  while (I < L) { // Start searching the array
    V = A[I]; // Get the value

divmgl

function solution(X, A) {
  if (A.length === 1) { // If the array is one element
    // And if its first item is 1 as well as the value to search for,
    // the frog doesn't need to move
    if (A[0] === 1 && X === 1) return 0; 
    // If not, it's impossible to go anywhere
    else return -1;
  }
    
  var i = -1, // Counter