import java.util.Scanner;

public class _1370 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        int digitos = in.nextInt();
        int cliques = in.nextInt();
        String saida = "";
        String parte2 = "";

        for (int i = 1; i <= cliques; i++){
            saida += in.nextInt();
        }

        for (int i = cliques+1; i <= digitos; i ++){
            parte2 += in.nextInt();
        }

        parte2 += saida;

        System.out.println( parte2.substring(0,10) );
    }
}

you are using in.nextInt() to get the input from the user for a String. That is used for integers. You should be using in.next() or in.nextLine() for String.