<script>
const ispossible = (arr, n) => {
let possibility1 = new Array(n).fill(0);
for (let i = 0; i < n; i++)
possibility1[i] = i + arr[0];
let possibility2 = new Array(n).fill(0);
for (let i = 0; i < n; i++)
possibility2[i] = i + arr[0] + 1;
let possibility3 = new Array(n);
for (let i = 0; i < n; i++)
possibility3[i] = i + arr[0] - 1;
let canposs1 = true, canposs2 = true;
let canposs3 = true;
for (let i = 0; i < n; i++) {
if (Math.abs(possibility1[i] - arr[i]) > 1) {
canposs1 = false;
break;
}
}
for (let i = 0; i < n; i++) {
if (Math.abs(possibility2[i] - arr[i]) > 1) {
canposs2 = false;
break;
}
}
for (let i = 0; i < n; i++) {
if (Math.abs(possibility3[i] - arr[i]) > 1) {
canposs3 = false;
break;
}
}
if (canposs1 || canposs2 || canposs3) {
return true;
}
return false;
}
let N = 4;
let arr = [1, 2, 3, 7];
if (ispossible(arr, N)) {
document.write("YES");
}
else {
document.write("NO");
}
</script>