C++ :

#include <cstdlib>
#include <cstdio>
#include <algorithm>
#define INF 20005
#define eps 1e-6
#define maxn 100005
using namespace std;
struct glass{
    double t, c;
    glass(double t, double c) : t(t), c(c){}
    glass(){}
}save[maxn];
int dcmp(double a, double b){
    if (a - b > eps) return 1;
    else if (b - a > eps) return -1;
    return 0;
}
bool cmp(glass a, glass b){
    if (a.t != b.t) return dcmp(a.t, b.t) < 0;
    return dcmp(a.c, b.c) < 0;
}
double C, T;
int n;
bool judge(double x){
    double all = 0;
    for (int i = 0; i < n; i++){
        all += save[i].c * (x - save[i].t) / (T - x);
    }
    if (dcmp(C, all) >= 0) return true;
    return false;
}
double work(double l, double r){
    if (r - l < eps) return l;
    double mid = ((r - l) / 2) + l;
    if (judge(mid)) return work(mid, r);
    else return work(l, mid);
}
int main(){
    scanf("%d", &n);
    scanf("%lf%lf", &T, &C);
    for (int i = 0; i < n; i++){
        scanf("%lf%lf", &save[i].t, &save[i].c);
    }
    sort(save, save + n, cmp);
    if (dcmp(T, save[0].t) >= 0 && dcmp(T, save[n - 1].t) <= 0){
        for (int i = 0; i < n; i++){
            if(dcmp(T, save[i].t) != 0){
                printf("Impossible\n");
                return 0;
            }
        }
        printf("Possible\n%.4lf", save[0].t);
        return 0;
    }
    if (dcmp(T, save[0].t) < 0){
        if (judge(save[0].t)){
            printf("Possible\n%.4lf", save[0].t);
        }
        else printf("Impossible\n");
    }
    else{
        if (!judge(save[n - 1].t - eps)){
            printf("Impossible\n");
            return 0;
        }
        printf("Possible\n%.4lf", work(save[n - 1].t, T));
    }
    return 0;
}