[编程题]
<
#include<stdio.h>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
using namespace std;
#define f(i,m,n) for(i=m;i<n;i++)
int main()
{
int i,n;
cin >> n;
vector<int> v(n);
f(i, 0, n) {
cin >> v[i];
}
sort(v.begin(), v.end());
int val = v[1] - v[0];
int sub;
bool flag=true;
f(i, 1, n - 1) {
sub = v[i+1] - v[i];
if (sub != val) {
flag = false;
break;
}
}
if (flag) {
cout << "Possible";
}
else
{
cout << "Impossible";
}
return 0;
}