#include <bits/stdc++.h>
using namespace std;
int n, w, m, ct[55];
double cup[55][55], bol[55], peo[55], p;
int main() {
  cin >> n >> w >> m;
  p = (double)n * w / m;
  if (w > p * 2) {
    cout << "NO" << endl;
    return 0;
  }
  bool flag = 0;
  for (int i = 1; i <= n; ++i) bol[i] = w;
  for (int i = 1; i <= m; ++i) {
    for (int j = 1; j <= n; ++j)
      if (bol[j] > 1e-6) {
        double d = min(p - peo[i], bol[j]);
        cup[i][j] += d;
        peo[i] += d;
        bol[j] -= d;
        if (d > 1e-6) ct[j]++;
        if (ct[j] > 2) flag = 1;
      }
  }
  if (flag) {
    printf("NO\n");
    return 0;
  }
  printf("YES\n");
  for (int i = 1; i <= m; ++i) {
    for (int j = 1; j <= n; ++j)
      if (cup[i][j] > 1e-6) printf("%d %.8lf ", j, cup[i][j]);
    printf("\n");
  }
  return 0;
}
