#include <bits/stdc++.h>
using namespace std;
int main() {
  int m, n, w;
  cin >> n >> w >> m;
  double per = 1.0 * n * w / m;
  if (m > n * 2) {
    puts("NO");
    return 0;
  }
  if (m <= n) {
    puts("YES");
    int bottle = 1;
    double rest = 1.0 * w;
    for (int cup = 1; cup <= m; cup++) {
      double need = per;
      while (need > 0) {
        double amount = min(rest, need);
        if (bottle > n) break;
        printf("%d %.9lf ", bottle, amount);
        need -= amount;
        rest -= amount;
        if (rest == 0.0) bottle++, rest = 1.0 * w;
      }
      puts("");
    }
    return 0;
  }
  if (n % (m - n) == 0) {
    double rest = 1.0 * w - per;
    int group = n / (m - n);
    puts("YES");
    for (int cup = 1; cup <= n; cup++) printf("%d %.9lf\n", cup, per);
    for (int cup = 1; cup <= m - n; cup++) {
      for (int i = (cup - 1) * group + 1; i <= cup * group; i++)
        printf("%d %.9lf ", i, rest);
      puts("");
    }
  } else
    puts("NO");
  return 0;
}
