用Python写的然后超时了

import math
n,m,r = map(int,input().split())
dist = 0
count = 0
num0 = [[0]*n for i in range(n)]
num=[]
for i in range(m):
    num.append(input().split())
for i in range(m):
    for j in range(n):
        for k in range(n):
            dist=math.sqrt((int(num[i][0])-1-j)**2+(int(num[i][1])-1-k)**2)
            if dist<=r and num0[j][k]==0:
                count+=1
                num0[j][k]=1
print(count)