import java.io.IOException;
import java.io.InputStream;
import java.util.InputMismatchException;

public class Main {
	public static void main(String[] args) {
		new Main();
	}

	public Main() {
		FasterScanner sc = new FasterScanner(System.in);

		long n = sc.nextInt();
		long sol = n*(n+1)/2;
		long n3 = n/3;
		sol -= 3*n3*(n3+1)/2;
		long n5 = n/5;
		sol -= 5*n5*(n5+1)/2;
		long n15 = n/15;
		sol += 15*n15*(n15+1)/2;
		
		System.out.println(sol);
		
		sc.close();
	}
	
	class FasterScanner {
		private InputStream mIs;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public FasterScanner() {
			this(System.in);
		}

		public FasterScanner(InputStream is) {
			mIs = is;
		}

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public String nextString() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

		public void close() {
			try {
				mIs.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
} import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.util.InputMismatchException; InputMismatchException java.util public class Main {
	public static void main(String[] args) {
		new Main();
	}

	public Main() {
		FasterScanner sc = new FasterScanner(System.in);

		long n = sc.nextInt();
		long sol = n*(n+1)/2;
		long n3 = n/3;
		sol -= 3*n3*(n3+1)/2;
		long n5 = n/5;
		sol -= 5*n5*(n5+1)/2;
		long n15 = n/15;
		sol += 15*n15*(n15+1)/2;
		
		System.out.println(sol);
		
		sc.close();
	}
	
	class FasterScanner {
		private InputStream mIs;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public FasterScanner() {
			this(System.in);
		}

		public FasterScanner(InputStream is) {
			mIs = is;
		}

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public String nextString() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

		public void close() {
			try {
				mIs.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
} Main public static void main(String[] args) {
		new Main();
	} main {
		new Main();
	} new Main() String[] args args public Main() {
		FasterScanner sc = new FasterScanner(System.in);

		long n = sc.nextInt();
		long sol = n*(n+1)/2;
		long n3 = n/3;
		sol -= 3*n3*(n3+1)/2;
		long n5 = n/5;
		sol -= 5*n5*(n5+1)/2;
		long n15 = n/15;
		sol += 15*n15*(n15+1)/2;
		
		System.out.println(sol);
		
		sc.close();
	} Main {
		FasterScanner sc = new FasterScanner(System.in);

		long n = sc.nextInt();
		long sol = n*(n+1)/2;
		long n3 = n/3;
		sol -= 3*n3*(n3+1)/2;
		long n5 = n/5;
		sol -= 5*n5*(n5+1)/2;
		long n15 = n/15;
		sol += 15*n15*(n15+1)/2;
		
		System.out.println(sol);
		
		sc.close();
	} FasterScanner sc = new FasterScanner(System.in); sc new FasterScanner(System.in) long n = sc.nextInt(); n sc.nextInt() sc.nextInt sc long sol = n*(n+1)/2; sol n*(n+1)/2 n*(n+1) n (n+1) n 1 2 long n3 = n/3; n3 n/3 n 3 sol -= 3*n3*(n3+1)/2 sol 3*n3*(n3+1)/2 3*n3*(n3+1) 3*n3*(n3+1) 3 n3 (n3+1) n3 1 2 long n5 = n/5; n5 n/5 n 5 sol -= 5*n5*(n5+1)/2 sol 5*n5*(n5+1)/2 5*n5*(n5+1) 5*n5*(n5+1) 5 n5 (n5+1) n5 1 2 long n15 = n/15; n15 n/15 n 15 sol += 15*n15*(n15+1)/2 sol 15*n15*(n15+1)/2 15*n15*(n15+1) 15*n15*(n15+1) 15 n15 (n15+1) n15 1 2 System.out.println(sol) System.out.println System.out System System.out sol sc.close() sc.close sc class FasterScanner {
		private InputStream mIs;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public FasterScanner() {
			this(System.in);
		}

		public FasterScanner(InputStream is) {
			mIs = is;
		}

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public String nextString() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

		public void close() {
			try {
				mIs.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	} FasterScanner private InputStream mIs; mIs private byte[] buf = new byte[1024]; buf new byte[1024] 1024 private int curChar; curChar private int numChars; numChars public FasterScanner() {
			this(System.in);
		} FasterScanner {
			this(System.in);
		} this(System.in) this System.in System System.in public FasterScanner(InputStream is) {
			mIs = is;
		} FasterScanner {
			mIs = is;
		} mIs = is mIs is InputStream is is public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		} read {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		} if (numChars == -1)
				throw new InputMismatchException(); numChars == -1 numChars -1 1 throw new InputMismatchException(); new InputMismatchException() if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			} curChar >= numChars curChar numChars {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			} curChar = 0 curChar 0 try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				} catch (IOException e) {
					throw new InputMismatchException();
				} IOException e {
					throw new InputMismatchException();
				} throw new InputMismatchException(); new InputMismatchException() {
					numChars = mIs.read(buf);
				} numChars = mIs.read(buf) numChars mIs.read(buf) mIs.read mIs buf if (numChars <= 0)
					return -1; numChars <= 0 numChars 0 return -1; -1 1 return buf[curChar++]; buf[curChar++] buf curChar++ curChar public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		} nextLine {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		} int c = read(); c read() read while (isSpaceChar(c))
				c = read(); isSpaceChar(c) isSpaceChar c c = read() c read() read StringBuilder res = new StringBuilder(); res new StringBuilder() do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c)); !isEndOfLine(c) isEndOfLine(c) isEndOfLine c {
				res.appendCodePoint(c);
				c = read();
			} res.appendCodePoint(c) res.appendCodePoint res c c = read() c read() read return res.toString(); res.toString() res.toString res public String nextString() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		} nextString {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		} int c = read(); c read() read while (isSpaceChar(c))
				c = read(); isSpaceChar(c) isSpaceChar c c = read() c read() read StringBuilder res = new StringBuilder(); res new StringBuilder() do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c)); !isSpaceChar(c) isSpaceChar(c) isSpaceChar c {
				res.appendCodePoint(c);
				c = read();
			} res.appendCodePoint(c) res.appendCodePoint res c c = read() c read() read return res.toString(); res.toString() res.toString res public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		} nextLong {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		} int c = read(); c read() read while (isSpaceChar(c))
				c = read(); isSpaceChar(c) isSpaceChar c c = read() c read() read int sgn = 1; sgn 1 if (c == '-') {
				sgn = -1;
				c = read();
			} c == '-' c '-' {
				sgn = -1;
				c = read();
			} sgn = -1 sgn -1 1 c = read() c read() read long res = 0; res 0 do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c)); !isSpaceChar(c) isSpaceChar(c) isSpaceChar c {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} if (c < '0' || c > '9')
					throw new InputMismatchException(); c < '0' || c > '9' c < '0' c '0' c > '9' c '9' throw new InputMismatchException(); new InputMismatchException() res *= 10 res 10 res += c - '0' res c - '0' c '0' c = read() c read() read return res * sgn; res * sgn res sgn public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		} nextInt {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		} int c = read(); c read() read while (isSpaceChar(c))
				c = read(); isSpaceChar(c) isSpaceChar c c = read() c read() read int sgn = 1; sgn 1 if (c == '-') {
				sgn = -1;
				c = read();
			} c == '-' c '-' {
				sgn = -1;
				c = read();
			} sgn = -1 sgn -1 1 c = read() c read() read int res = 0; res 0 do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c)); !isSpaceChar(c) isSpaceChar(c) isSpaceChar c {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} if (c < '0' || c > '9')
					throw new InputMismatchException(); c < '0' || c > '9' c < '0' c '0' c > '9' c '9' throw new InputMismatchException(); new InputMismatchException() res *= 10 res 10 res += c - '0' res c - '0' c '0' c = read() c read() read return res * sgn; res * sgn res sgn public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		} isSpaceChar {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		} return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1; c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1 c == '\t' c == '\r' c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1 c == ' ' c ' ' c == '\n' c '\n' c == '\r' c '\r' c == '\t' c '\t' c == -1 c -1 1 int c c public boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		} isEndOfLine {
			return c == '\n' || c == '\r' || c == -1;
		} return c == '\n' || c == '\r' || c == -1; c == '\n' || c == '\r' || c == -1 c == '\n' || c == '\r' || c == -1 c == '\n' c '\n' c == '\r' c '\r' c == -1 c -1 1 int c c public void close() {
			try {
				mIs.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		} close {
			try {
				mIs.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		} try {
				mIs.close();
			} catch (IOException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			} IOException e {
				e.printStackTrace();
			} e.printStackTrace() e.printStackTrace e {
				mIs.close();
			} mIs.close() mIs.close mIs public class Main {
	public static void main(String[] args) {
		new Main();
	}

	public Main() {
		FasterScanner sc = new FasterScanner(System.in);

		long n = sc.nextInt();
		long sol = n*(n+1)/2;
		long n3 = n/3;
		sol -= 3*n3*(n3+1)/2;
		long n5 = n/5;
		sol -= 5*n5*(n5+1)/2;
		long n15 = n/15;
		sol += 15*n15*(n15+1)/2;
		
		System.out.println(sol);
		
		sc.close();
	}
	
	class FasterScanner {
		private InputStream mIs;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public FasterScanner() {
			this(System.in);
		}

		public FasterScanner(InputStream is) {
			mIs = is;
		}

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public String nextString() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

		public void close() {
			try {
				mIs.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
} public class Main {
	public static void main(String[] args) {
		new Main();
	}

	public Main() {
		FasterScanner sc = new FasterScanner(System.in);

		long n = sc.nextInt();
		long sol = n*(n+1)/2;
		long n3 = n/3;
		sol -= 3*n3*(n3+1)/2;
		long n5 = n/5;
		sol -= 5*n5*(n5+1)/2;
		long n15 = n/15;
		sol += 15*n15*(n15+1)/2;
		
		System.out.println(sol);
		
		sc.close();
	}
	
	class FasterScanner {
		private InputStream mIs;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public FasterScanner() {
			this(System.in);
		}

		public FasterScanner(InputStream is) {
			mIs = is;
		}

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public String nextString() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

		public void close() {
			try {
				mIs.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
} Main
import java.io.IOException;
import java.io.InputStream;
import java.util.InputMismatchException;

public class Main {
	public static void main(String[] args) {
		new Main();
	}

	public Main() {
		FasterScanner sc = new FasterScanner(System.in);

		long n = sc.nextInt();
		long sol = n*(n+1)/2;
		long n3 = n/3;
		sol -= 3*n3*(n3+1)/2;
		long n5 = n/5;
		sol -= 5*n5*(n5+1)/2;
		long n15 = n/15;
		sol += 15*n15*(n15+1)/2;
		
		System.out.println(sol);
		
		sc.close();
	}
	
	class FasterScanner {
		private InputStream mIs;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public FasterScanner() {
			this(System.in);
		}

		public FasterScanner(InputStream is) {
			mIs = is;
		}

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = mIs.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public String nextString() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

		public void close() {
			try {
				mIs.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}
