Read integers from standard input, separated by spaces or newlines, until end of input (`EOF`). Determine and print how many **distinct** values appear in the sequence. **The data are read from standard input** (in the format described), not from a file. Use `while (cin >> x)` to detect end of input. Input: One or more lines contain integers, separated by spaces or newlines. - the total number of values read is between `0` and `1000` - values are integers between `-1.000.000` and `1.000.000` Output: The program prints to standard output a single non-negative integer: how many distinct values were read. If the input is empty, the program prints `0`. Example: Input: 1 2 3 2 1 4 5 3 Output: 5