function fibo(n) {
if (typeof n != "number" || isNaN(n)) {
return -1;
}
if (n < 0) {
return -1;
}
if (n === 0) {
return 0;
}
let a = 1;
let b = 1;
let result = 1;
for (let i = 2; i < n; i++) {
result = a + b;
b = a;
a = result;
}
return result;
}
module.exports = {
fibo,
};