#include <bits/stdc++.h>
using namespace std;
const double EPS = 1e-9;
int n, w, m;
double val[100];
struct node {
  int ind;
  double cost;
  node(int ind = -1, double cost = -1) : ind(ind), cost(cost) {}
};
vector<node> Q[100];
int main() {
  cin >> n >> w >> m;
  for (int i = 1; i <= n; i++) val[i] = 1;
  int poi = 1;
  for (int i = 1; i <= m; i++) {
    double t = (double)n / (double)m;
    while (t > EPS) {
      double tmp = min(val[poi], t);
      t -= tmp;
      val[poi] -= tmp;
      Q[i].push_back(node(poi, (double)w * tmp));
      if (val[poi] < EPS) poi++;
    }
  }
  for (int i = 1; i <= n; i++) {
    int cnt = 0;
    for (int j = 1; j <= m; j++)
      for (int z = 0; z < (int)Q[j].size(); z++)
        if (Q[j][z].ind == i) {
          cnt++;
        }
    if (cnt > 2) {
      cout << "NO" << endl;
      return 0;
    }
  }
  cout << "YES" << endl;
  for (int i = 1; i <= m; i++) {
    for (int j = 0; j < (int)Q[i].size(); j++)
      cout << fixed << setprecision(10) << Q[i][j].ind << ' ' << Q[i][j].cost
           << ' ';
    cout << endl;
  }
  return 0;
}
