>>> import re
>>> 
>>> pat = r'[A-Z]{3}[a-z]{3}\d{4}'
>>> 
>>> s = 'aaaABCDabc12345aaaABCDabc12345aaa'
>>> 
>>> n = len(re.findall(pat, s))
>>> print(n)
2
>>>

# -*- coding: UTF-8 -*-
n = 7
def main(): 
    out = ['a%s' % ('b'*k) for k in xrange(1, n)]
    out.append('a')
    print ''.join(out)
if __name__ == '__main__':
    main()

'%sa' % 'a'.join('b'*i for i in range(n))

110010
101010
010100
001011
110100
000100

with open('graph.dat') as f:
    data = [l.strip() for l in f]
def edges(data):
    for r, rd in enumerate(data, 1):
        for c, cd in enumerate(rd, 1):
            if int(cd):
                yield r, c
for r, c in edges(data):
    print r, c

>>> 
1 1
1 2
1 5
2 1
2 3
2 5
3 2
3 4
4 3
4 5
4 6
5 1
5 2
5 4
6 4
>>> 

i = 1
result = []
with open('test.txt') as fin:
    for line in fin:
        j = 1
        for char in line.rstrip():
            if char == '1':
                result.append([i, j])
            j += 1
        i += 1

 result.append([i, j])

result.append((i, j))