Stopwatch

Robin just received a stopwatch from her grandfather. Robin’s stopwatch has a single button. Pressing the button alternates between stopping and starting the stopwatch’s timer. When the timer is on, the displayed time increases by 1 every second.

Initially the stopwatch is stopped and the timer reads 0 seconds. Given a sequence of times that the stopwatch button is pressed, determine what the stopwatch’s timer displays.

The first line of input contains a single integer $N$ ($1 \leq N \leq 1\, 000$), which is the number of times the stopwatch was pressed.

The next $N$ lines describe the times the stopwatch’s button was pressed in increasing order. Each line contains a single integer $t$ ($0 \leq t \leq 10^6$), which is the time the button was pressed. No two button presses happen on the same second.

Display `still running` if the
stopwatch’s timer is still running after all button presses
were made. Otherwise display the number of seconds displayed on
the stopwatch’s timer.

Sample Input 1 | Sample Output 1 |
---|---|

2 7 11 |
4 |

Sample Input 2 | Sample Output 2 |
---|---|

5 2 5 9 10 17 |
still running |

Sample Input 3 | Sample Output 3 |
---|---|

4 0 2 104 117 |
15 |