Teachers and parrents

Instructions:

The table describes the number of passengers entering and leaving at stations A, B, C ... Bus arrives without passengers at the first station. All passengers get off on the last station. We do keep rules of decency - first get off and then get in.

Example

 
A
B
C
D
E
 got off 
0 0
0 3
0 1
1 1
7 8
 got on 
3 7
0 0
 in bus
1 3
3 3
 altogether
15


Solution

 
A
B
C
D
E
 got off 
0 0
0 3
0 1
1 1
7 8
 got on 
1 3
2 3
2 0
3 7
0 0
 in bus
1 3
3 3
5 2
7 8
 altogether
4
6
7
15


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