(Amounts in thousands of Mexican pesos)
| For the year ended 31 December  | 
      ||||
|---|---|---|---|---|
| 2018 | 2017 | |||
| Operating activities | ||||
| Income (loss) before income tax | 
      Ps. | 163,694 | Ps. | (539,445) | 
    
| Items not affecting cash flows: | ||||
| Depreciation and amortization | 2,124,184 | 2,042,366 | ||
| Interest income | (47,391) | (22,238) | ||
| Interest expense | 1,591,543 | 1,525,335 | ||
| Foreign exchange loss, net | 394,980 | 479,301 | 
    ||
| Net periodic benefit cost | 1,133 | 708 | ||
| 4,228,143 | 3,486,027 | |||
| Changes in operating assets and liabilities: | ||||
| Accounts receivable | (48,833) | (39,812)         | 
    ||
| Related parties | 30,335 | (71,857) | ||
| Other current and non-current assets | 23,322 | 54,270 | 
    ||
| Accounts payable and accrued liabilities | (121,305) | 23,871 | 
    ||
| Taxes and contributions payable | (917,878) | (339,596) | ||
| Net cash flows from operating activities | 3,193,784 | 3,112,903         | 
    ||
| Investing activities | ||||
| Interest received | 47,391 | 22,238         | 
    ||
| Licenses and software | (4,469) | (9,796)         | 
    ||
| Property and equipment | (1,317,087) | (1,410,845) | 
    ||
| Net cash flows used in investing activities | (1,274,165) | (1,398,403) | ||
| Financing activities | ||||
| Payment of short-term debt | 58,349 | - | ||
| Short-term debt | - | 1,672,772 | ||
| Issuance of short-term debt | - | (1,555,000) | ||
| Structured note premium | - | (15,930) | ||
| Interest paid on short-term debt | (1,572,492) | (1,486,398) | ||
| Net cash flows used in financing activities | (1,514,143) | (1,384,556) | 
    ||
| Net increase in cash and cash equivalents | 405,476 | 329,944 | ||
| Cash and cash equivalents at beginning of the year | 561,477 | 231,533 | 
    ||
| Cash and cash equivalents at end of the year | Ps. | 966,953 | Ps. | 561,477 | 
The accompanying notes are an integral part of these financial statements.