using namespace std;
#include <iostream>
#include <cmath>

int main() {

    int n, endT;
    double perc;

    cin >> n >> perc >> endT;

    int curT=0, newT;
    double res = 0;
    for (int i=0; i<n; i++) {
        cin >> newT;
        double add = (newT-curT)*(1+i*perc/100);
        res += add;
        curT = newT;
    }
    double add = (endT-curT)*(1+n*perc/100);
    res += add;

    printf("%.9f\n", res);
    return 0;
}