N,M = map(int,input().split())
C = list(map(int,input().split()))
C = sorted(C)
counter = 0
answer = 0
while counter < M+1 :
    C[0] = C[0] - 1
    counter += 1
    if C[0] == 0 and counter < M:
        C.pop(C[0])
        answer += 1
    else :
        C = sorted(C)
    if len(C) == 0 :
        break
print(answer)