Compilare: user.cpp: In function ‘void citire()’: user.cpp:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result user.cpp: In function ‘void build_graph()’: user.cpp:109: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void solve()’: user.cpp:128: warning: comparison between signed and unsigned integer expressions user.cpp:132: warning: comparison between signed and unsigned integer expressions