#include <bits/stdc++.h>
using namespace std;
int n, m, l, k, r, i, j, a[105], p, t, d, e[105], ii, w;
vector<pair<int, int> > c[105];
int main() {
  cin >> n >> w >> m;
  for (int i = 0; i < n; i++) a[i] = m;
  d = 0;
  for (int i = 0; i < m; i++) {
    int t = n;
    while (t > a[d]) {
      t -= a[d];
      e[d]++;
      c[i].push_back(pair<int, int>(d, a[d]));
      d++;
    }
    a[d] -= t, e[d]++;
    c[i].push_back(pair<int, int>(d, t));
    if (a[d] == 0) d++;
  }
  for (ii = 0; ii < m; ii++)
    if (e[ii] > 2) break;
  if (ii != m)
    puts("NO");
  else {
    puts("YES");
    for (int i = 0; i < m; i++) {
      for (int j = 0; j < c[i].size(); j++)
        printf("%d %.8lf ", c[i][j].first + 1,
               (double)(c[i][j].second) / m * w);
      cout << endl;
    }
  }
  return 0;
}
