#include <bits/stdc++.h>
using namespace std;

int main() {
	int n; cin >> n;
    vector<int> vec(n);
    for(auto& z:vec)
        cin >> z;
    for(int i=n-1; i>0; i--)
    {
        vec[i]-=vec[i-1];
        //cerr << vec[i] << " ";
    }
    map<int,int> m;
    for(auto& z:vec)
        m[z]++;
    cout << m.size()+1 << "\n";
    int rn=1;
    cout << rn << " ";
    for(auto& [a,b]:m)
    {
        rn+=b;
        cout << rn << " ";
    }
}