N, M = [int(i) for i in input().split(' ')]
SC = []
for _ in range(M):
    SC.append([int(i) for i in input().split(' ')])

for n in range(10**(N-1),10**N):
    n = list(str(n))
    flg = 0
    for s,c in SC:
        if not n[s-1] == str(c):
            flg = 1

    if flg == 0:
        print(''.formatjoin(n))
        exit()