/* 
   AOJ 2018
   Princess's Gamble
   2015.4.26
 */

#include<stdio.h>

int calc(int num_athlete, int winner, int deduction_rate)
{
  int i, sum_votes = 0, sum_pay = 0, one_pay = 0, ballot_box[100] = {0};
  
  for(i = 0; i < num_athlete; i++){
    scanf("%d", &ballot_box[i]);
    sum_votes += ballot_box[i];
  }
  
  sum_pay = sum_votes * (100 - deduction_rate);
  
  if(ballot_box[winner - 1] == 0)
    {
      return 0;
    }
  else
    {
      one_pay = sum_pay / ballot_box[winner - 1];
      
      return one_pay;
    }

}

int main(void)
{
  int n, m, p, dividend;
  while(1)
    {
      scanf("%d %d %d", &n, &m, &p);
      if(n == 0 && m == 0 && p == 0)
	{
	  break;
	}

      dividend = calc(n, m, p);
      printf("%d\n", dividend);
    }
  return 0;
}