#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, w, m;
  scanf("%d%d%d", &n, &w, &m);
  if (n < m && m % (m - n)) return puts("NO");
  puts("YES");
  int now = 1, use = 0;
  for (int i = 1; i <= m; i++) {
    int div = 0;
    for (int k = 0; div < n; k++) {
      int cnt = min(n - div, m - use);
      use += cnt;
      div += cnt;
      printf(" %d %.12f" + !k, now, cnt * 1.0 / m * w);
      if (use == m) {
        now++;
        use = 0;
      }
    }
    puts("");
  }
}
