def calcs(s):
    s = '+'+s
    out = 0
    i = 0
    one = act = ''
    while i <=len(s)-1:
        if s[i] == '+':
            act = '+'
            i+=1
            continue
        elif s[i] == '-':
            act = '-'
            i+=1
            continue
        else:
            while s[i].isdigit():
                one += s[i]
                i+=1
                if i > len(s)-1:
                    break
        if act == '+':
            out += int(one)
        else:
            out-= int(one)
        one = ''
    return out
print(calcs('1+2+3-2-1+0+13-16'))

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