#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, w, m;
  scanf("%d%d%d", &n, &w, &m);
  if (m > n && n % (m - n)) {
    puts("NO");
    return 0;
  }
  puts("YES");
  int j = 1;
  double re = w, val;
  for (int i = 0; i < m; i++) {
    val = n * w * 1.0 / m;
    while (val > 0.0000001) {
      if (re - val > 0.0000001) {
        printf("%d %lf ", j, val);
        re -= val;
        val = 0;
      } else {
        printf("%d %lf ", j, re);
        val -= re;
        j++;
        re = w;
      }
    }
    cout << endl;
  }
  return 0;
}
