import sys

def main():
    input = sys.stdin.read
    data = input().split()
    idx = 0
    N = int(data[idx])
    idx += 1
    M = int(data[idx])
    idx += 1
    
    out_degree = [0] * (N + 1)
    in_degree = [0] * (N + 1)
    
    for _ in range(M):
        u = int(data[idx])
        idx += 1
        v = int(data[idx])
        idx += 1
        out_degree[u] += 1
        in_degree[v] += 1
    
    deltas = []
    for u in range(1, N + 1):
        delta = out_degree[u] - in_degree[u]
        deltas.append(delta)
    
    sum_positive = sum(d for d in deltas if d > 0)
    
    if sum_positive == 0:
        # All deltas are zero
        min_k = 0
    else:
        K_case1 = sum_positive
        K_case2 = sum_positive - 1
        min_k = min(K_case1, K_case2)
    
    print(min_k)

if __name__ == "__main__":
    main()