#include <bits/stdc++.h>
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define fast ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
#define all(v) v.begin(),v.end()
#define pb push_back
#define sz size()
#define ft first
#define sd second
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef unsigned long long ull;
const int N = 1e6 + 5;
const ll M = 1e8;
const ll inf = 1e9;
const ll mod = 1e9;
const double Pi = acos(-1);
ll binpow(ll x, ll ti) { ll res = 1;while (ti){if(ti & 1)res *= x;x *= x;ti >>= 1; x %= mod; res %= mod;} return res;}
ll binmul(ll x, ll ti) { ll res = 0;while (ti){if(ti & 1)res += x;x += x;ti >>= 1; x %= mod; res %= mod;} return res;}
ll nok(ll a, ll b) { return (a*b)/__gcd(abs(a),abs(b)) * (a*b > 0 ? 1 : -1); }
bool odd(ll n) { return (n % 2 == 1); }
bool even(ll n) { return (n % 2 == 0); }
int n, k, a[N], sum;
vector <pair<pair<int, int>, int>> ans;
const void solve(/*Armashka*/) {
cin >> n >> k;
for (int i = 1; i <= n; ++ i) cin >> a[i], sum += a[i];
while (1) {
bool ok = 0;
vector <ll> e, o;
for (int i = 1; i <= n; ++ i) {
if (a[i] == 0) continue;
ok = 1;
if (even(a[i])) e.pb(i);
else o.pb(i);
}
if (!ok) break;
if (even(sum)) {
if (e.sz > 1) { -- a[e[0]], -- a[e[1]]; ans.pb({{e[0], e[1]}, 1}); continue; }
else if (o.sz > 1) { -- a[o[0]], -- a[o[1]]; ans.pb({{o[0], o[1]}, 1}); continue; }
else { cout << "-1\n"; return; }
} else {
if (e.sz && o.sz) {
-- a[e[0]], -- a[o[0]];
ans.pb({{e[0], o[0]}, 1});
} else {
cout << "-1\n";
return;
}
}
}
cout << ans.sz << "\n";
for (auto x : ans) cout << x.sd << " " << x.ft.ft << " " << x.ft.sd << "\n";
}
signed main() {
fast;
//freopen("divide.in", "r", stdin);
//freopen("divide.out", "w", stdout);
int tt = 1;
//cin >> tt;
while (tt --) {
solve();
}
}
/*
6 8
3 3 3 3
1 2 1 2
3 4 3 4
5 5 5 5
4 3 4 3
4 4 4 4
2 1 2 1
3 6 3 6
*/
/*
9 12
1 9 4
1 2 5
2 3 7
2 4 3
4 3 6
3 6 4
8 7 10
6 7 5
5 8 1
9 5 7
5 4 12
6 8 2
2
4 7
5
1 6
5 3
4 8
5 8
1 5
*/
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
204 KB |
n=4 |
| 2 |
Incorrect |
0 ms |
204 KB |
Jury has the answer but participant has not |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
204 KB |
n=4 |
| 2 |
Incorrect |
0 ms |
204 KB |
Jury has the answer but participant has not |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
204 KB |
n=4 |
| 2 |
Incorrect |
0 ms |
204 KB |
Jury has the answer but participant has not |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
9 ms |
204 KB |
Jury has the answer but participant has not |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
204 KB |
n=4 |
| 2 |
Incorrect |
0 ms |
204 KB |
Jury has the answer but participant has not |
| 3 |
Halted |
0 ms |
0 KB |
- |
