#include <stdio.h>
int main (){
    int x, y, p[50001], a, b;
    scanf ("%d %d", &x, &y);
    p[0]=0;
    for (int i = 1; i <= x; i++){
    scanf ("%d", &p[i]);
    p[i]=p[i] + p[i-1];
    }
    while (y--){
        scanf ("%d %d", &a, &b);
        printf ("Hari ke %d-%d: %.2f\n", a, b, (p[b]- p[a-1])/(b-a+1.0));

    }
    return 0;
}