#include <stdio.h>
#define N_MAX 100
#define PRICE 100

int vote[N_MAX + 1];

int main(void)
{
    int i, n, m, p, t, count, winners;

    while(scanf("%d %d %d", &n, &m, &p), n+m+p)
    {
        count = 0;

        /* 1 ... m-1 */
        for(i=1; i<m; i++)
        {
            scanf("%d", &t);
            count += t;
        }

        /* m */
        scanf("%d", &winners);
        count += winners;

        /* m+1 ... n */
        for(i=m+1; i<=n; i++)
        {
            scanf("%d", &t);
            count += t;
        }

        /* result */
        if(winners)
            printf("%d\n", (count * PRICE * (100 - p)) / (winners * 100));
        else
            puts("0");
    }

    return 0;
}