#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, w, m, j = 1;
  double pc, rb, rc;
  scanf("%d%d%d", &n, &w, &m);
  pc = double(n) * w / m;
  if ((m > n && m % (m - n) != 0) || (m > 2 * n)) {
    printf("NO");
    return 0;
  }
  rb = w;
  printf("YES\n");
  for (int i = 1; i <= m; i++) {
    rc = pc;
    while (rc > 0) {
      if (rc > rb) {
        if (rb > 1E-10) {
          printf("%d %.6f ", j, rb);
        }
        rc -= rb;
        rb = w;
        j++;
      } else {
        if (rc > 1E-10) {
          printf("%d %.6f ", j, rc);
        }
        rb -= rc;
        rc = 0;
      }
    }
    printf("\n");
  }
  return 0;
}
