k, n = map(int, input().split())
ops = list(map(int, input().split()))
increase = 0  
length = 1    
ls = []
for op in ops:
    if op == 0:
        length *= 2
    else:
        length += length
    ls.append(length)
for i in range(n - 1, -1, -1):
    half = ls[i] // 2
    if k > half:
        k -= half
        if ops[i] == 1:
            increase += 1
print(chr(ord('a') + (increase % 26)))