#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, w, m, cur = 1;
  cin >> n >> w >> m;
  double d = (double)n * w, f = w;
  d = d / m;
  double ost = 0;
  for (int i = 1; i <= m; ++i) {
    double f1 = d;
    f1 -= ost;
    ost = 0;
    if (f1 < -0.0000001) {
      printf("%s", "NO");
      return 0;
    }
    while (f1 >= w) f1 -= w;
    if (f1 > 0.0000001) ost = w - f1;
  }
  ost = 0;
  printf("%s\n", "YES");
  for (int i = 1; i <= m; ++i) {
    double f1 = d;
    if (ost > 0.0000001) {
      f1 -= ost;
      printf("%ld%c%.7lf%c", cur, ' ', ost, ' ');
      cur++;
    }
    ost = 0;
    while (f1 >= w) {
      f1 -= w;
      printf("%ld%c%.7lf%c", cur, ' ', (double)w, ' ');
      cur++;
    }
    if (f1 > 0.0000001) {
      ost = w - f1;
      printf("%ld%c%.7lf%c", cur, ' ', f1, ' ');
    }
    printf("\n");
  }
}
