randuri.cpp: In function 'int eval(int, int)': randuri.cpp:12: warning: NULL used in arithmetic randuri.cpp:13: warning: NULL used in arithmetic randuri.cpp: In function 'int main()': randuri.cpp:29: warning: unused variable 'aux' randuri.cpp:22: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result randuri.cpp:23: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result