output_description: Print the K-th smallest integer in the array after the N operations.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N K
      a_1 b_1
      :  
      a_N b_N
attempt: import sys
  N,K=map(int, input().split())
  p=[]
  for i in range (0,N):
    r=list(map(int, input().split() )) 
    p.append(r)
  p.sort()
  k=0
  for i in range(0,N):
    k+=p[i][0]]
    if k>=K:
      print(p[i][1])
      sys.exit()
  import sys
  N,K=map(int, input().split())
  p=[]
  for i in range (0,N):
    r=list(map(int, input().split() )) 
    p.append(r)
  p.sort()
  k=0
  for i in range(0,N):
    k+=p[i][1]
    if k>=K:
      print(p[i][0])
      sys.exit()
problem_description: Statement
  
  There is an empty array. The following N operations will be performed to
  insert integers into the array. In the i-th operation (1≤i≤N), b_i copies of
  an integer a_i are inserted into the array. Find the K-th smallest integer in
  the array after the N operations. For example, the 4-th smallest integer in
  the array \\{1,2,2,3,3,3\\} is 3.
samples: [{"input": "3 4\n    1 1\n    2 2\n    3 3", "output": "3\n    \n\nThe resulting array is the same as the one in the problem statement.\n\n* * *"}, {"input": "10 500000\n    1 100000\n    1 100000\n    1 100000\n    1 100000\n    1 100000\n    100000 100000\n    100000 100000\n    100000 100000\n    100000 100000\n    100000 100000", "output": "1"}]