#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void checkmin(T &a, T b) {
  if (a > b) a = b;
}
template <class T>
inline void checkmax(T &a, T b) {
  if (a < b) a = b;
}
const int oo = 1 << 30;
const double eps = 1e-7;
const int N = 1;
const int M = 1;
const long long P = 10000000097ll;
int n, w, m;
int last[128];
double use[128];
int fcmp(double a, double b) {
  if (a + eps < b) return -1;
  return a - eps > eps;
}
int can(int flag) {
  double now;
  int i;
  double tmp;
  int t;
  double v = n * w * 1.0 / m;
  if (m > 2 * n) return 0;
  now = v;
  t = -1;
  (memset((use), 0, sizeof(use)));
  int out;
  for ((i) = 0; i < (m); (i)++) {
    out = 0;
    while (fcmp(now, 0) > 0) {
      if (-1 == t || fcmp(use[t], w) >= 0) {
        t++;
        last[t] = i;
        use[t] = 0;
      }
      if (i - last[t] > 1) return 0;
      tmp = ((now) < (w - use[t]) ? (now) : (w - use[t]));
      if (flag) {
        if (out++) putchar(' ');
        printf("%d %f", t + 1, tmp);
      }
      use[t] += tmp;
      now -= tmp;
    }
    if (flag) puts("");
    now = v;
  }
  return 1;
}
int main() {
  int T, _ = 0;
  while (3 == scanf("%d %d %d", &n, &w, &m)) {
    if (can(0)) {
      puts("YES");
      can(1);
    } else
      puts("NO");
  }
  return 0;
}
