#include <bits/stdc++.h>
using namespace std;
const int INF = 1000000000;
const double EPS = 1e-8;
int main() {
  cout.setf(ios::fixed);
  cout.precision(6);
  int n, w, m;
  cin >> n >> w >> m;
  int total = n * w;
  double part = total / double(m);
  int act = 1, cnt = 0;
  bool ok = true;
  double rest = w;
  vector<vector<pair<int, double> > > v(m);
  for (int i = 0; i < m; ++i) {
    double fill = 0;
    while (fill + EPS < part) {
      double qtt = min(part - fill, rest);
      fill += qtt;
      rest -= qtt;
      ++cnt;
      if (cnt == 3) {
        ok = false;
        break;
      }
      v[i].push_back(pair<int, double>(act, qtt));
      if (rest < EPS) {
        rest = w;
        ++act;
        cnt = 0;
      }
    }
  }
  if (not ok)
    cout << "NO" << endl;
  else {
    cout << "YES" << endl;
    for (int i = 0; i < m; ++i) {
      for (int j = 0; j < v[i].size(); ++j) {
        if (j != 0) cout << " ";
        cout << v[i][j].first << " " << v[i][j].second;
      }
      cout << endl;
    }
  }
}
