#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, cnt, n, m, i, j, w, remain, b1;
  double tmp;
  scanf("%d%d%d", &n, &w, &m);
  cnt = 0;
  x = 0;
  for (i = 0; i < m; i++) {
    x += n;
    cnt++;
    if (cnt > 2) {
      printf("NO\n");
      return 0;
      ;
    }
    while (x >= m) {
      x -= m;
      if (x > 0)
        cnt = 1;
      else
        cnt = 0;
    }
  }
  printf("YES\n");
  x = 0;
  tmp = (double)w / m * n / n;
  j = 0;
  for (i = 0; i < m; i++) {
    remain = n;
    b1 = 0;
    while (x + remain >= m) {
      if (b1 != 0) printf(" ");
      b1 = 1;
      printf("%d %.6lf", j + 1, tmp * (m - x));
      remain -= (m - x);
      x = 0;
      j++;
    }
    if (remain > 0) {
      if (b1 != 0) printf(" ");
      b1 = 1;
      printf("%d %.6lf", j + 1, tmp * remain);
      x += remain;
    }
    printf("\n");
  }
  return 0;
}
