Hi, I am getting TLE in case:9 on IARCS, the code is below, can anyone suggest correction or a better approach:

if __name__ == "__main__":
    n1, n2, n3 = [int(x) for x in raw_input().split()]
 
    elements = {}
    for i in range(n1+n2+n3):
        x = input()
        elements[x] = elements.get(x, 0)+1
 
    X = [x for x in elements.keys() if elements[x] > 1]
    print len(X)
    for x in sorted(X):
        print x