Compilare: user.cpp:30:0: warning: "M_PI" redefined [enabled by default] #define M_PI 3.141592653589793 ^ In file included from /usr/include/c++/4.8/cmath:44:0, from /usr/include/c++/4.8/complex:44, from user.cpp:8: /usr/include/math.h:367:0: note: this is the location of the previous definition # define M_PI 3.14159265358979323846 /* pi */ ^ user.cpp: In function ‘int main()’: user.cpp:83:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("maxflow.in","r",stdin); ^ user.cpp:84:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("maxflow.out","w",stdout); ^