import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) {
		FastScanner sc = new FastScanner(System.in);
		int l = sc.nextInt();
		String val = String.valueOf(l);
		BigDecimal bd = new BigDecimal(val);
		BigDecimal three = new BigDecimal("3");
		BigDecimal bd1 = bd.divide(three, 3, BigDecimal.ROUND_DOWN);
		BigDecimal bd2 = bd.divide(three, 3 ,BigDecimal.ROUND_UP);
		
		BigDecimal ans = new BigDecimal("0");
		
		if(l%3 == 0) {
			ans = (bd1.multiply(bd1)).multiply(bd1);
		}else if(l%3 == 1) {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		}else {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		}
		
		System.out.println(ans);
	}
	
	static class FastScanner {
		private BufferedReader reader = null;
	    private StringTokenizer tokenizer = null;
	    public FastScanner(InputStream in) {
	        reader = new BufferedReader(new InputStreamReader(in));
	        tokenizer = null;
	    }

	    public String next() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return tokenizer.nextToken();
	    }

	    public String nextLine() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }

	        return tokenizer.nextToken("\n");
	    }

	    public long nextLong() {
	        return Long.parseLong(next());
	    }

	    public int nextInt() {
	        return Integer.parseInt(next());
	    }

	    public double nextDouble() {
	         return Double.parseDouble(next());
	     }

	    public int[] nextIntArray(int n) {
	        int[] a = new int[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextInt();
	        return a;
	    }

	    public long[] nextLongArray(int n) {
	        long[] a = new long[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextLong();
	        return a;
	    }
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.InputStreamReader; InputStreamReader java.io import java.math.BigDecimal; BigDecimal java.math import java.util.StringTokenizer; StringTokenizer java.util public class Main {
	public static void main(String[] args) {
		FastScanner sc = new FastScanner(System.in);
		int l = sc.nextInt();
		String val = String.valueOf(l);
		BigDecimal bd = new BigDecimal(val);
		BigDecimal three = new BigDecimal("3");
		BigDecimal bd1 = bd.divide(three, 3, BigDecimal.ROUND_DOWN);
		BigDecimal bd2 = bd.divide(three, 3 ,BigDecimal.ROUND_UP);
		
		BigDecimal ans = new BigDecimal("0");
		
		if(l%3 == 0) {
			ans = (bd1.multiply(bd1)).multiply(bd1);
		}else if(l%3 == 1) {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		}else {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		}
		
		System.out.println(ans);
	}
	
	static class FastScanner {
		private BufferedReader reader = null;
	    private StringTokenizer tokenizer = null;
	    public FastScanner(InputStream in) {
	        reader = new BufferedReader(new InputStreamReader(in));
	        tokenizer = null;
	    }

	    public String next() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return tokenizer.nextToken();
	    }

	    public String nextLine() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }

	        return tokenizer.nextToken("\n");
	    }

	    public long nextLong() {
	        return Long.parseLong(next());
	    }

	    public int nextInt() {
	        return Integer.parseInt(next());
	    }

	    public double nextDouble() {
	         return Double.parseDouble(next());
	     }

	    public int[] nextIntArray(int n) {
	        int[] a = new int[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextInt();
	        return a;
	    }

	    public long[] nextLongArray(int n) {
	        long[] a = new long[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextLong();
	        return a;
	    }
	}
} Main public static void main(String[] args) {
		FastScanner sc = new FastScanner(System.in);
		int l = sc.nextInt();
		String val = String.valueOf(l);
		BigDecimal bd = new BigDecimal(val);
		BigDecimal three = new BigDecimal("3");
		BigDecimal bd1 = bd.divide(three, 3, BigDecimal.ROUND_DOWN);
		BigDecimal bd2 = bd.divide(three, 3 ,BigDecimal.ROUND_UP);
		
		BigDecimal ans = new BigDecimal("0");
		
		if(l%3 == 0) {
			ans = (bd1.multiply(bd1)).multiply(bd1);
		}else if(l%3 == 1) {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		}else {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		}
		
		System.out.println(ans);
	} main {
		FastScanner sc = new FastScanner(System.in);
		int l = sc.nextInt();
		String val = String.valueOf(l);
		BigDecimal bd = new BigDecimal(val);
		BigDecimal three = new BigDecimal("3");
		BigDecimal bd1 = bd.divide(three, 3, BigDecimal.ROUND_DOWN);
		BigDecimal bd2 = bd.divide(three, 3 ,BigDecimal.ROUND_UP);
		
		BigDecimal ans = new BigDecimal("0");
		
		if(l%3 == 0) {
			ans = (bd1.multiply(bd1)).multiply(bd1);
		}else if(l%3 == 1) {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		}else {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		}
		
		System.out.println(ans);
	} FastScanner sc = new FastScanner(System.in); sc new FastScanner(System.in) int l = sc.nextInt(); l sc.nextInt() sc.nextInt sc String val = String.valueOf(l); val String.valueOf(l) String.valueOf String l BigDecimal bd = new BigDecimal(val); bd new BigDecimal(val) BigDecimal three = new BigDecimal("3"); three new BigDecimal("3") BigDecimal bd1 = bd.divide(three, 3, BigDecimal.ROUND_DOWN); bd1 bd.divide(three, 3, BigDecimal.ROUND_DOWN) bd.divide bd three 3 BigDecimal.ROUND_DOWN BigDecimal BigDecimal.ROUND_DOWN BigDecimal bd2 = bd.divide(three, 3 ,BigDecimal.ROUND_UP); bd2 bd.divide(three, 3 ,BigDecimal.ROUND_UP) bd.divide bd three 3 BigDecimal.ROUND_UP BigDecimal BigDecimal.ROUND_UP BigDecimal ans = new BigDecimal("0"); ans new BigDecimal("0") if(l%3 == 0) {
			ans = (bd1.multiply(bd1)).multiply(bd1);
		}else if(l%3 == 1) {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		}else {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		} l%3 == 0 l%3 l 3 0 {
			ans = (bd1.multiply(bd1)).multiply(bd1);
		} ans = (bd1.multiply(bd1)).multiply(bd1) ans (bd1.multiply(bd1)).multiply(bd1) (bd1.multiply(bd1)).multiply (bd1.multiply(bd1)) bd1.multiply bd1 bd1 bd1 if(l%3 == 1) {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		}else {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		} l%3 == 1 l%3 l 3 1 {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		} ans = (bd1.multiply(bd1)).multiply(bd2) ans (bd1.multiply(bd1)).multiply(bd2) (bd1.multiply(bd1)).multiply (bd1.multiply(bd1)) bd1.multiply bd1 bd1 bd2 {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		} ans = (bd1.multiply(bd2)).multiply(bd2) ans (bd1.multiply(bd2)).multiply(bd2) (bd1.multiply(bd2)).multiply (bd1.multiply(bd2)) bd1.multiply bd1 bd2 bd2 System.out.println(ans) System.out.println System.out System System.out ans String[] args args static class FastScanner {
		private BufferedReader reader = null;
	    private StringTokenizer tokenizer = null;
	    public FastScanner(InputStream in) {
	        reader = new BufferedReader(new InputStreamReader(in));
	        tokenizer = null;
	    }

	    public String next() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return tokenizer.nextToken();
	    }

	    public String nextLine() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }

	        return tokenizer.nextToken("\n");
	    }

	    public long nextLong() {
	        return Long.parseLong(next());
	    }

	    public int nextInt() {
	        return Integer.parseInt(next());
	    }

	    public double nextDouble() {
	         return Double.parseDouble(next());
	     }

	    public int[] nextIntArray(int n) {
	        int[] a = new int[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextInt();
	        return a;
	    }

	    public long[] nextLongArray(int n) {
	        long[] a = new long[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextLong();
	        return a;
	    }
	} FastScanner private BufferedReader reader = null; reader null private StringTokenizer tokenizer = null; tokenizer null public FastScanner(InputStream in) {
	        reader = new BufferedReader(new InputStreamReader(in));
	        tokenizer = null;
	    } FastScanner {
	        reader = new BufferedReader(new InputStreamReader(in));
	        tokenizer = null;
	    } reader = new BufferedReader(new InputStreamReader(in)) reader new BufferedReader(new InputStreamReader(in)) tokenizer = null tokenizer null InputStream in in public String next() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return tokenizer.nextToken();
	    } next {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return tokenizer.nextToken();
	    } if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        } try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            } IOException e {
	                throw new RuntimeException(e);
	            } throw new RuntimeException(e); new RuntimeException(e) {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public String nextLine() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }

	        return tokenizer.nextToken("\n");
	    } nextLine {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }

	        return tokenizer.nextToken("\n");
	    } if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        } try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            } IOException e {
	                throw new RuntimeException(e);
	            } throw new RuntimeException(e); new RuntimeException(e) {
	                return reader.readLine();
	            } return reader.readLine(); reader.readLine() reader.readLine reader return tokenizer.nextToken("\n"); tokenizer.nextToken("\n") tokenizer.nextToken tokenizer "\n" public long nextLong() {
	        return Long.parseLong(next());
	    } nextLong {
	        return Long.parseLong(next());
	    } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next public int nextInt() {
	        return Integer.parseInt(next());
	    } nextInt {
	        return Integer.parseInt(next());
	    } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public double nextDouble() {
	         return Double.parseDouble(next());
	     } nextDouble {
	         return Double.parseDouble(next());
	     } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public int[] nextIntArray(int n) {
	        int[] a = new int[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextInt();
	        return a;
	    } nextIntArray {
	        int[] a = new int[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextInt();
	        return a;
	    } int[] a = new int[n]; a new int[n] n for (int i = 0; i < n; i++)
	            a[i] = nextInt(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i a[i] = nextInt(); a[i] = nextInt() a[i] a i nextInt() nextInt return a; a int n n public long[] nextLongArray(int n) {
	        long[] a = new long[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextLong();
	        return a;
	    } nextLongArray {
	        long[] a = new long[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextLong();
	        return a;
	    } long[] a = new long[n]; a new long[n] n for (int i = 0; i < n; i++)
	            a[i] = nextLong(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i a[i] = nextLong(); a[i] = nextLong() a[i] a i nextLong() nextLong return a; a int n n public class Main {
	public static void main(String[] args) {
		FastScanner sc = new FastScanner(System.in);
		int l = sc.nextInt();
		String val = String.valueOf(l);
		BigDecimal bd = new BigDecimal(val);
		BigDecimal three = new BigDecimal("3");
		BigDecimal bd1 = bd.divide(three, 3, BigDecimal.ROUND_DOWN);
		BigDecimal bd2 = bd.divide(three, 3 ,BigDecimal.ROUND_UP);
		
		BigDecimal ans = new BigDecimal("0");
		
		if(l%3 == 0) {
			ans = (bd1.multiply(bd1)).multiply(bd1);
		}else if(l%3 == 1) {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		}else {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		}
		
		System.out.println(ans);
	}
	
	static class FastScanner {
		private BufferedReader reader = null;
	    private StringTokenizer tokenizer = null;
	    public FastScanner(InputStream in) {
	        reader = new BufferedReader(new InputStreamReader(in));
	        tokenizer = null;
	    }

	    public String next() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return tokenizer.nextToken();
	    }

	    public String nextLine() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }

	        return tokenizer.nextToken("\n");
	    }

	    public long nextLong() {
	        return Long.parseLong(next());
	    }

	    public int nextInt() {
	        return Integer.parseInt(next());
	    }

	    public double nextDouble() {
	         return Double.parseDouble(next());
	     }

	    public int[] nextIntArray(int n) {
	        int[] a = new int[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextInt();
	        return a;
	    }

	    public long[] nextLongArray(int n) {
	        long[] a = new long[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextLong();
	        return a;
	    }
	}
} public class Main {
	public static void main(String[] args) {
		FastScanner sc = new FastScanner(System.in);
		int l = sc.nextInt();
		String val = String.valueOf(l);
		BigDecimal bd = new BigDecimal(val);
		BigDecimal three = new BigDecimal("3");
		BigDecimal bd1 = bd.divide(three, 3, BigDecimal.ROUND_DOWN);
		BigDecimal bd2 = bd.divide(three, 3 ,BigDecimal.ROUND_UP);
		
		BigDecimal ans = new BigDecimal("0");
		
		if(l%3 == 0) {
			ans = (bd1.multiply(bd1)).multiply(bd1);
		}else if(l%3 == 1) {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		}else {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		}
		
		System.out.println(ans);
	}
	
	static class FastScanner {
		private BufferedReader reader = null;
	    private StringTokenizer tokenizer = null;
	    public FastScanner(InputStream in) {
	        reader = new BufferedReader(new InputStreamReader(in));
	        tokenizer = null;
	    }

	    public String next() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return tokenizer.nextToken();
	    }

	    public String nextLine() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }

	        return tokenizer.nextToken("\n");
	    }

	    public long nextLong() {
	        return Long.parseLong(next());
	    }

	    public int nextInt() {
	        return Integer.parseInt(next());
	    }

	    public double nextDouble() {
	         return Double.parseDouble(next());
	     }

	    public int[] nextIntArray(int n) {
	        int[] a = new int[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextInt();
	        return a;
	    }

	    public long[] nextLongArray(int n) {
	        long[] a = new long[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextLong();
	        return a;
	    }
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) {
		FastScanner sc = new FastScanner(System.in);
		int l = sc.nextInt();
		String val = String.valueOf(l);
		BigDecimal bd = new BigDecimal(val);
		BigDecimal three = new BigDecimal("3");
		BigDecimal bd1 = bd.divide(three, 3, BigDecimal.ROUND_DOWN);
		BigDecimal bd2 = bd.divide(three, 3 ,BigDecimal.ROUND_UP);
		
		BigDecimal ans = new BigDecimal("0");
		
		if(l%3 == 0) {
			ans = (bd1.multiply(bd1)).multiply(bd1);
		}else if(l%3 == 1) {
			ans = (bd1.multiply(bd1)).multiply(bd2);
		}else {
			ans = (bd1.multiply(bd2)).multiply(bd2);
		}
		
		System.out.println(ans);
	}
	
	static class FastScanner {
		private BufferedReader reader = null;
	    private StringTokenizer tokenizer = null;
	    public FastScanner(InputStream in) {
	        reader = new BufferedReader(new InputStreamReader(in));
	        tokenizer = null;
	    }

	    public String next() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return tokenizer.nextToken();
	    }

	    public String nextLine() {
	        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                return reader.readLine();
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }

	        return tokenizer.nextToken("\n");
	    }

	    public long nextLong() {
	        return Long.parseLong(next());
	    }

	    public int nextInt() {
	        return Integer.parseInt(next());
	    }

	    public double nextDouble() {
	         return Double.parseDouble(next());
	     }

	    public int[] nextIntArray(int n) {
	        int[] a = new int[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextInt();
	        return a;
	    }

	    public long[] nextLongArray(int n) {
	        long[] a = new long[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextLong();
	        return a;
	    }
	}
}