N = int(input())
S = list(input())
ans = []
count = 1
for i in range(N - 1):
    if S[i] != S[i + 1]:
        ans.append(count)
        count = 1
    else:
        count += 1
ans.append(count)
nokori = 26 - len(ans)
ans_after = list(map(str, ans))
print("".join(ans_after) + str(nokori * "0"))
# print(a)