#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-6;
int dcmp(double x) {
  if (fabs(x) < eps)
    return 0;
  else
    return x < 0 ? -1 : 1;
}
const int N = 55;
double a[N]{0};
vector<pair<int, double> > p[N];
int main() {
  double w;
  int n, m;
  cin >> n >> w >> m;
  int j = 0;
  double x = 1.0 * n * w / m;
  bool flag = 1;
  if (n * 2 < m) flag = 0;
  for (int i = 1; i <= n; i++) {
    double t = x - a[j];
    if (dcmp(t) < 0)
      flag = 0;
    else if (dcmp(t) == 0) {
      j = (j + 1) % m;
      t = x - a[j];
    }
    if (dcmp(w - t) >= 0) {
      if (dcmp(t) != 0) p[j].push_back({i, t});
      t = w - t;
      a[j] = x;
      j = (j + 1) % m;
      a[j] += t;
      if (dcmp(t) != 0) p[j].push_back({i, t});
    } else {
      p[j].push_back({i, w});
      a[j] += w;
    }
  }
  if (!flag)
    puts("NO");
  else {
    puts("YES");
    for (int i = 0; i < m; i++) {
      for (int j = 0; j < p[i].size(); j++) {
        printf("%d %.6f ", p[i][j].first, p[i][j].second);
      }
      puts("");
    }
  }
  return 0;
}
