Huawei od search for the same substring

Here are two for you character string t and p , Demand from t And one of them p The same continuous substring , And output the subscript of the first character of the string .

Input description :

The input file consists of two lines , Each represents a string t and p , Guarantee t The length of is not less than p , And t Not more than 1000000,p Not more than 10000.

Output description :

If you can get from t And one of them p Equal continuous substrings , Then the first character of the substring is output in t Subscript in （ The subscripts are... From left to right 1,2,3,…）; Output if not ”No”; If there are multiple such substrings , The first character with the smallest subscript is output .

let a = readLine();
	let b = readLine();
	// let a = "AVERDXIVYERDIAN";
	// let b = "RDXI";
	 
	if(a.length>1000000||b.length>a.length||b.length>10000){
	    console.log("No");
	}
	 
	console.log(a.indexOf(b) == -1? "No" : a.indexOf(b)+1);