#include <bits/stdc++.h>
using i64 = long long;
#ifdef DEBUG
#include "../../../debug.h"
#else
#define debug(...) void(23)
#endif
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int N, K;
std::cin >> N >> K;
std::vector<i64> A(N);
for (int i = 0; i < N; ++i) {
std::cin >> A[i];
}
i64 sum = std::accumulate(A.begin(), A.end(), 0LL);
if (sum % K != 0) {
std::cout << "-1\n";
return 0;
}
i64 gsiz = sum / K;
int cur = 0;
i64 now = 0;
std::vector<std::deque<std::pair<i64, i64>>> g(K);
for (int i = 0; i < N; ++i) {
if (A[i] > gsiz) {
std::cout << "-1\n";
return 0;
}
if (now + A[i] > gsiz) {
g[cur].emplace_back(gsiz - now, i);
++cur;
now = now + A[i] - gsiz;
g[cur].emplace_back(now, i);
} else {
now += A[i];
g[cur].emplace_back(A[i], i);
if (now == gsiz) {
++cur;
now = 0;
}
}
}
std::vector<std::vector<i64>> ans;
while (true) {
debug(g);
ans.push_back({});
i64 take = g[0].front().first;
for (int i = 0; i < K; ++i) {
take = std::min(take, g[i].front().first);
}
ans.back().emplace_back(take);
for (int i = 0; i < K; ++i) {
ans.back().emplace_back(g[i].front().second);
g[i].front().first -= take;
if (g[i].front().first == 0) {
g[i].pop_front();
}
}
int bad = 0;
for (int i = 0; i < K; ++i) {
bad += g[i].empty();
}
assert(bad == 0 || bad == K);
if (bad == K) {
break;
}
}
std::cout << int(ans.size()) << '\n';
for (auto& v : ans) {
std::cout << v[0] << ' ';
for (int i = 1; i <= K; ++i) {
std::cout << v[i] + 1 << " \n"[i == K];
}
}
return 0;
}
