---

import sys

def main():
    data = sys.stdin.read().split()
    n = int(data[0])
    a = data[1:1 + n]
    b = data[1 + n:1 + 2 * n]
    prev = 0
    ans = 0
    for i in range(n):
        d = int(b[i]) - int(a[i])
        if d < 0:
            print("NO SOLUTION")
            return
        if d > prev:
            ans += d - prev
        prev = d
    print(ans)

main()