#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
struct pt {
    ll x, y;
};

bool cmp (pt a, pt b) {
    return a.x < b.x || a.x == b.x && a.y < b.y;
}

bool cw (pt a, pt b, pt c) {
    return a.x*(b.y-c.y)+b.x*(c.y-a.y)+c.x*(a.y-b.y) < 0;
}

bool ccw (pt a, pt b, pt c) {
    return a.x*(b.y-c.y)+b.x*(c.y-a.y)+c.x*(a.y-b.y) > 0;
}

void convex_hull (vector<pt> & a) {
    if (a.size() == 1)  return;
    sort (a.begin(), a.end(), &cmp);
    pt p1 = a[0],  p2 = a.back();
    vector<pt> up, down;
    up.push_back (p1);
    down.push_back (p1);
    for (size_t i=1; i<a.size(); ++i) {
        if (i==a.size()-1 || cw (p1, a[i], p2)) {
            while (up.size()>=2 && !cw (up[up.size()-2], up[up.size()-1], a[i]))
                up.pop_back();
            up.push_back (a[i]);
        }
        if (i==a.size()-1 || ccw (p1, a[i], p2)) {
            while (down.size()>=2 && !ccw (down[down.size()-2], down[down.size()-1], a[i]))
                down.pop_back();
            down.push_back (a[i]);
        }
    }
    a.clear();
    for (size_t i=0; i<up.size(); ++i)
        a.push_back (up[i]);
    for (size_t i=down.size()-2; i>0; --i)
        a.push_back (down[i]);
}
ll area(pt a, pt b, pt c) {
    return abs(a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y));
}
bool inside(pt a, pt b, pt c, pt d) {
    return area(a, b, c) == area(a, b, d) + area(a, c, d) + area(b, c, d);
}
bool inside_poly(pt x, vector < pt >& all) {
    if (all.size() <= 2) return false;
    for (int j = 1; j + 1 < all.size(); j++) {
        if (inside(all[0], all[j], all[j + 1], x)) return true;
    }
    return false;
}
int n;
const int maxN = 1005;
pt t[maxN];
int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    //freopen("input.txt", "r", stdin);
    cin >> n;
    bool ok = true;
    vector < pt > ch;
    for (int i = 1; i <= n; i++) {
        cin >> t[i].x >> t[i].y;
        if (inside_poly(t[i], ch)) {
            ok = false;
            break;
        }
        ch.push_back(t[i]);
        convex_hull(ch);
    }
    ch.clear();
    for (int i = n; i >= 1; i--) {
        if (inside_poly(t[i], ch)) {
            ok = false;
            break;
        }
        ch.push_back(t[i]);
        convex_hull(ch);
    }
    if (ok) cout << "Possible";
    else cout << "Impossible";
    return 0;
}