#include <bits/stdc++.h>
using namespace std;
int rank[100005], father[100005], counti[53];
vector<pair<int, double>> ans[53];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n, w, m;
  cin >> n >> w >> m;
  double cap = 1.0 * n * w / m, eps = 1e-6;
  int cbnum = 1;
  double cbleft = w, more = cap;
  for (int i = 1; i <= m; i++) {
    while (cbleft < more + eps) {
      ans[i].push_back({cbnum, cbleft});
      counti[cbnum]++;
      cbnum++;
      more -= cbleft;
      cbleft = w;
    }
    if (more > eps) {
      cbleft -= more;
      ans[i].push_back({cbnum, more});
      counti[cbnum]++;
    }
    more = cap;
  }
  for (int i = 1; i <= n; i++) {
    if (counti[i] > 2) {
      cout << "NO\n";
      return 0;
    }
  }
  cout << "YES\n";
  for (int i = 1; i <= m; i++) {
    for (int j = 0; j < ans[i].size(); j++) {
      cout << fixed << setprecision(7) << ans[i][j].first << " "
           << ans[i][j].second << " ";
    }
    cout << "\n";
  }
  return 0;
}
