comp.py

#!/usr/bin/env python3

def comp(s):
    l = []
    for i in s.split():
        l.append(int(i))

    o = "" 
    for i in range(0,len(l)):
        if i == 0:
            o += str(l[i]) + " "
        elif l[i] == l[i-1]+1:
            o += str(l[i]) + " "
            t = o.rsplit(" ", 2)
            t[0] = t[0][0]+"-"
            t[1] += " "
            o = "".join(t)
        else:
            o += str(l[i]) + " "
    print(o)



if __name__ == '__main__':
    s = input()
    comp(s)