desert.cpp: In function 'int main()': desert.cpp:10: error: 'n' was not declared in this scope desert.cpp:10: error: 'k' was not declared in this scope desert.cpp:10: error: 'p' was not declared in this scope desert.cpp:8: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result desert.cpp:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result