#include <bits/stdc++.h>
using namespace std;
int i, j, k, m, n, a[51][51], s[51];
double w;
bool doit() {
  k = 1;
  for (i = 1; i <= n; i++) s[i] = m;
  for (i = 1; i <= m; i++) {
    if (s[k] >= n) {
      a[k][i] = n;
      s[k] -= n;
      if (!s[k]) k++;
    } else if (s[k] + s[k + 1] >= n) {
      a[k][i] = s[k];
      s[k + 1] -= (n - s[k]);
      a[k + 1][i] = (n - s[k]);
      k++;
      if (!s[k]) k++;
    } else
      return false;
  }
  return true;
}
int main() {
  cin >> m >> w >> n;
  if (doit()) {
    cout.precision(10);
    cout << "YES" << endl;
    for (i = 1; i <= n; i++) {
      for (j = 1; j <= m; j++)
        if (a[i][j] > 0) cout << j << " " << w * a[i][j] / n << " ";
      cout << endl;
    }
  } else
    cout << "NO";
  return 0;
}
