#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys

if __name__ == '__main__':
    freq = 0
    matches = {0: 1}

    while True:
        with open("input.txt") as fp:
            line = fp.readline()
            while line:

                if line[:1] == "+":
                    freq += int(line[1:])
                else:
                    freq -= int(line[1:])

                if freq not in matches:
                    matches[freq] = 1
                else:
                    print("Frequency reached twice: {}".format(freq))
                    sys.exit()

                line = fp.readline()