#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, w, m;
  cin >> n >> w >> m;
  vector<double> a(n, w);
  vector<int> c(n);
  vector<vector<pair<int, double>>> res;
  for (int i(0); i < m; ++i) {
    double q = double(n) * w / m;
    vector<pair<int, double>> v;
    for (int j(0); j < n; ++j) {
      double h = min(q, a[j]);
      if (h > 1e-9) {
        v.push_back({j + 1, h});
        q -= h;
        a[j] -= h;
        if (++c[j] > 2) {
          puts("NO");
          return 0;
        }
      }
    }
    res.push_back(v);
  }
  puts("YES");
  for (auto t : res) {
    for (auto q : t) printf("%d %.8lf ", q.first, q.second);
    puts("");
  }
  return 0;
}
