import java.util.Scanner;
import java.lang.Math;
public class Main {
    public static void main (String...args) {
        Scanner sc = new Scanner(System.in); int a = sc.nextInt(); int b = sc.nextInt(); int answer = -1;
        for (int i=b*10; i<(b+1)*10; i++) if (i*8/100==a){ answer = i; break;}
        System.out.println(answer);}
} import java.util.Scanner; Scanner java.util import java.lang.Math; Math java.lang public class Main {
    public static void main (String...args) {
        Scanner sc = new Scanner(System.in); int a = sc.nextInt(); int b = sc.nextInt(); int answer = -1;
        for (int i=b*10; i<(b+1)*10; i++) if (i*8/100==a){ answer = i; break;}
        System.out.println(answer);}
} Main public static void main (String...args) {
        Scanner sc = new Scanner(System.in); int a = sc.nextInt(); int b = sc.nextInt(); int answer = -1;
        for (int i=b*10; i<(b+1)*10; i++) if (i*8/100==a){ answer = i; break;}
        System.out.println(answer);} main {
        Scanner sc = new Scanner(System.in); int a = sc.nextInt(); int b = sc.nextInt(); int answer = -1;
        for (int i=b*10; i<(b+1)*10; i++) if (i*8/100==a){ answer = i; break;}
        System.out.println(answer);} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int answer = -1; answer -1 1 for (int i=b*10; i<(b+1)*10; i++) if (i*8/100==a){ answer = i; break;} int i=b*10; int i=b*10; i b*10 b 10 i<(b+1)*10 i (b+1)*10 (b+1) b 1 10 i++ i++ i if (i*8/100==a){ answer = i; break;} if (i*8/100==a){ answer = i; break;} i*8/100==a i*8/100 i*8 i 8 100 a { answer = i; break;} answer = i answer i break; System.out.println(answer) System.out.println System.out System System.out answer String...args args public class Main {
    public static void main (String...args) {
        Scanner sc = new Scanner(System.in); int a = sc.nextInt(); int b = sc.nextInt(); int answer = -1;
        for (int i=b*10; i<(b+1)*10; i++) if (i*8/100==a){ answer = i; break;}
        System.out.println(answer);}
} public class Main {
    public static void main (String...args) {
        Scanner sc = new Scanner(System.in); int a = sc.nextInt(); int b = sc.nextInt(); int answer = -1;
        for (int i=b*10; i<(b+1)*10; i++) if (i*8/100==a){ answer = i; break;}
        System.out.println(answer);}
} Main
import java.util.Scanner;
import java.lang.Math;
public class Main {
    public static void main (String...args) {
        Scanner sc = new Scanner(System.in); int a = sc.nextInt(); int b = sc.nextInt(); int answer = -1;
        for (int i=b*10; i<(b+1)*10; i++) if (i*8/100==a){ answer = i; break;}
        System.out.println(answer);}
}