#include <bits/stdc++.h>
using namespace std;
double EPS = 1e-9;
int INF = 2147483647;
const int MAXLEN = 51;
int A[MAXLEN][MAXLEN];
int used[MAXLEN];
int alpha[MAXLEN];
int n, m;
double w;
int main() {
  cin >> n >> w >> m;
  cout << setprecision(6);
  cout << fixed;
  int c = n * n;
  for (int i = 0; i < n; i++) used[i] = n * m;
  int sum = 0;
  for (int i = 0; i < m; i++) {
    sum = 0;
    for (int j = 0; j < n; j++) {
      if (sum == c) break;
      if (used[j] != 0)
        if (used[j] > c - sum && alpha[j] != 1)
          used[j] -= c - sum, A[i][j] += c - sum, sum = c, alpha[j]++;
        else
          sum += used[j], A[i][j] += used[j], used[j] = 0;
    }
    if (sum != c) {
      cout << "NO" << endl;
      return 0;
    }
  }
  cout << "YES" << endl;
  for (int i = 0; i < m; i++) {
    for (int j = 0; j < n; j++) {
      if (A[i][j] != 0)
        cout << j + 1 << " " << double(A[i][j]) / double(n * m) * w << " ";
    }
    cout << endl;
  }
  return 0;
}
