Problem:
 Score: 400 points    Problem Statement  In Takahashi Kingdom, there is a east-west railroad and N cities along it, numbered 1 , 2 , 3 , ..., N from west to east.
A company called AtCoder Express possesses M trains, and the train i runs from City L_i to City R_i (it is possible that L_i = R_i ).
Takahashi the king is interested in the following Q matters:   The number of the trains that runs strictly within the section from City p_i to City q_i , that is, the number of trains j such that p_i \leq L_j and R_j \leq q_i .   Although he is genius, this is too much data to process by himself. Find the answer for each of these Q queries to help him.      Constraints   N is an integer between 1 and 500 (inclusive).  M is an integer between 1 and 200 \ 000 (inclusive).  Q is an integer between 1 and 100 \ 000 (inclusive).  1 \leq L_i \leq R_i \leq N  (1 \leq i \leq M)  1 \leq p_i \leq q_i \leq N  (1 \leq i \leq Q)         Input  Input is given from Standard Input in the following format:  N  M  Q  L_1  R_1  L_2  R_2  :  L_M  R_M  p_1  q_1  p_2  q_2  :  p_Q  q_Q       Output  Print Q lines. The i -th line should contain the number of the trains that runs strictly within the section from City p_i to City q_i .        Sample Input 1 2 3 1
1 1
1 2
2 2
1 2      Sample Output 1 3  As all the trains runs within the section from City 1 to City 2 , the answer to the only query is 3 .       Sample Input 2 10 3 2
1 5
2 8
7 10
1 7
3 10      Sample Output 2 1
1  The first query is on the section from City 1 to 7 . There is only one train that runs strictly within that section: Train 1 .
The second query is on the section from City 3 to 10 . There is only one train that runs strictly within that section: Train 3 .       Sample Input 3 10 10 10
1 6
2 9
4 5
4 7
4 7
5 8
6 6
6 7
7 9
10 10
1 8
1 9
1 10
2 8
2 9
2 10
3 8
3 9
3 10
1 10      Sample Output 3 7
9
10
6
8
9
6
7
8
10

Solution (Python):
N, M, Q = map(int, input().split())

X = [[0 for j in range(510)] for i in range(510)]
C = [[0 for j in range(510)] for i in range(510)]

LR = []
for i in range(M):
    L, R = map(int, input().split())
    X[L][R] += 1

for i in range(1, N+1):
    for j in range(1, N+1):
        C[i][j] = C[i][j-1]+X[i][j]


for i in range(Q):
    p, q = map(int, input().split())
    sum = 0
    for j in range(p, q+1):
        sum += C[j][q]-C[j][p-1]
    print(sum)

Solution (Python):
import sys
input=sys.stdin.readline

n,m,q=map(int,input().split())
p=[[0]*(n+1) for _ in range(n+1)]
for i in range(m):
    l,r=map(int,input().split())
    p[l][r]+=1
for i in range(1,n+1):
    for j in range(1,n+1):
        p[i][j]+=p[i][j-1]
for i in range(1,n+1):
    for j in range(1,n+1):
        p[i][j]+=p[i-1][j]
for i in range(q):
    l,r=map(int,input().split())
    print(p[r][r]+p[l-1][l-1]-p[l-1][r]-p[r][l-1])