from math import pow, ceil, floor

lines = [l.split() for l in open("input.txt", 'r').read().splitlines()]
races = [(int(lines[0][i]), int(lines[1][i])) for i in range(1,len(lines[0]))]
#[(time, record)]

#d = t * v
#charge + t = time
#t = time - charge
#v = charge
#d = (time - charge) * charge
#d = -charge^2 + time*charge

summa = 1

for race in races:
    a = -1
    b = race[0]
    c = -race[1]
    rangeStart = floor((-b + pow((pow(b,2)-(4*a*c)),0.5)) / (2*a)) + 1
    rangeEnd = ceil((-b - pow((pow(b,2)-(4*a*c)),0.5)) / (2*a)) - 1
    summa *= (rangeEnd-rangeStart+1)

print(summa)