Compilare: user.cpp: In function ‘int main()’: user.cpp:218: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp: In function ‘void read()’: user.cpp:54: warning: ‘x1’ may be used uninitialized in this function user.cpp:54: warning: ‘x2’ may be used uninitialized in this function user.cpp:54: warning: ‘y1’ may be used uninitialized in this function