from re import split
import sys
n,m= map(int,sys.stdin.readline().split())
costs = [n]
#print(costs)
for line in sys.stdin:
a,b = map(int,line.split())
if a <= n:
costs.append(n-b)
#print(costs)
costs.sort()
print(costs[0])

from re import split
import sys
n,m= map(int,sys.stdin.readline().split())
costs = [n]
#print(costs)
for line in sys.stdin:
a,b = map(int,line.split())
if a <= n:
costs.append(n-b)
#print(costs)
costs.sort()
print(costs[0])