#include <bits/stdc++.h>
using namespace std;
double e = 0.0000001;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, w, m;
  cin >> n >> w >> m;
  double dn = n, dw = w, dm = m;
  bool check = true;
  double val = dn * dw / dm;
  int j = 0;
  double due = 0;
  for (int i = 0; i < m; ++i) {
    if (due > val + e) check = 0;
    double curr = due;
    for (; j < n && curr + e < val; ++j) {
      curr += w;
    }
    due = curr - val;
  }
  cout << setprecision(15);
  if (check) {
    due = 0;
    j = 1;
    cout << "YES\n";
    for (int i = 0; i < m; ++i) {
      if (due > e) cout << j - 1 << " " << due << " ";
      double curr = due;
      for (; j <= n && curr + e < val; ++j) {
        curr += w;
        if (curr + e < val)
          cout << j << " " << w << " ";
        else
          cout << j << " " << val - (curr - w) << " ";
      }
      due = curr - val;
      cout << "\n";
    }
  }
  if (!check) cout << "NO\n";
  return 0;
}
