Forth

#include <bits/stdc++.h>
#define F first
#define S second
using namespace std;
typedef long long ll;
typedef long double ld;

int check(vector<string> ans, int x){
	assert(ans.size()>=1);
	vector<int> s={1};
	for (string t : ans){
		if (t=="DUP"){
			assert(s.size()>=1);
			s.push_back(s.back());
		} else if (t=="+"){
			assert(s.size()>=2);
			int su=s.back()+s[(int)s.size()-2];
			s.pop_back();
			s.pop_back();
			s.push_back(su);
		} else if (t=="DROP"){
			s.pop_back();
		} else {
			assert(0);
		}
	}
	return s.size() == 1 && s.back()==x;
}

void solve(){
	int x;
	cin>>x;
	vector<int> s = {1};
	vector<string> ans;

	int ss=1;
	int su=1;
	int ba=1;
	for (int i=0;i<23;i++){
		if (su == x) break;
		assert(su<x);
		if ((1<<i) & x){
			ans.push_back("DUP");
			su+=ba;
			ss++;
			if (su==x) break;
			ans.push_back("DUP");
			su+=ba;
			ss++;
			if (su==x) break;
			ans.push_back("+");
			ba*=2;
			ss--;
		} else {
			ans.push_back("DUP");
			su+=ba;
			ss++;
			if (su==x) break;
			ans.push_back("+");
			ba*=2;
			ss--;
		}
	}
	assert(su==x);
	while (ss>1){
		ans.push_back("+");
		ss--;
	}
	if (x==1){
		ans.push_back("DUP");
		ans.push_back("DROP");
	}
	assert(check(ans,x));
	cout<<ans.size()<<endl;
	for (auto t : ans){
		cout<<t<<" ";
	}
	cout<<endl;
}

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	solve();
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED