pat-1002.py

# http://pat.zju.edu.cn/contests/pat-a-practise/1002
import sys
import math
buf = [0.0] * 1001

def read_line():
  line = sys.stdin.readline().split()
  index = 1
  length = len(line)
  
  while index < length:
    exp = int(line[index])
    coe = float(line[index + 1])
    buf[exp] += coe
    index += 2
    
def main():
  read_line()
  read_line()
  
  cnt = 0
  index = 1000
  ans = []
  while index >= 0:
    if math.fabs(buf[index]) > 1e-6:
      ans.append([index, buf[index]])
      cnt += 1
    index -= 1
    pass
  
  if cnt:
    print cnt,
    for item in ans:
      s = "%d %.1f" % (item[0], item[1])
      print s,
  else:
    print cnt


if __name__ == "__main__":
  main()