#include <bits/stdc++.h>
int main() {
  int n, w, m;
  scanf("%d%d%d", &n, &w, &m);
  int flg = 0;
  for (int i = 0; i < m; i++) {
    int a = (i * n) / m;
    int b = ((i + 1) * n) / m;
    if (a == b)
      if (((i * n) % m) && (((i + 1) * n) % m)) flg = 1;
  }
  if (flg)
    printf("NO");
  else {
    printf("YES");
    for (int i = 0; i < m; i++) {
      printf("\n");
      int a = (n * i) / m;
      int b = (n * (i + 1)) / m;
      double ca = ((n * i) % m) / (double)m;
      double cb = ((n * (i + 1)) % m) / (double)m;
      if (a == b)
        printf("%d %lf ", a + 1, (((double)n) / m) * w);
      else {
        printf("%d %lf ", a + 1, (1.0 - ca) * w);
        for (int i = a + 1; i < b; i++) {
          printf("%d %lf ", i + 1, 1.0 * w);
        }
        if (cb > .0) printf("%d %lf ", b + 1, w * cb);
      }
    }
  }
  return 0;
}
