In a train
journey, there are N stations between station A and B (The train starts from
station A). The number of passengers who alighted in station B is passed as the
input. The number of passengers who alighted and boarded in the N stations in
between is also passed as the input. The program must print the number of
passengers who boarded the train at station A.
Input
Format:
The first line
contains N and the number of passengers who alighted at station B (which is the
last station), separated by a space. N lines containing the number of
passengers who alighted and boarded the train in the N stations in between A
and B, with the values separated by a space.
Output
Format:
The first line
contains the number of passengers who boarded the train at station A.
Boundary
Conditions: 1 <= N <= 50
Example
Input/Output 1:
Input:
3 50
30 40
40 10
60 30
Output:
100
Explanation:
There are 3
stations in between A and B. 100 passengers boarded the train at station A. In
the 2nd station (first after A), 30 got down and 40 boarded the train. So now
passengers in the train is 100-30+40 = 110 In the 3rd station (second after A),
40 got down and 10 boarded. So passengers left in the train = 110-40+10 = 80 In
the 4th station, passengers left in the train = 80-60+30 = 50. These 50
passengers will alight in the last station which is station B.
Solution:
n,b=[int(i) for i
in input().split()]
for i in range(n):
x,y=[int(i) for i in input().split()]
a=b+x-y
b=a
print(a)