Compilare: user.cpp: In function 'bool reduce()': user.cpp:47: warning: comparison between signed and unsigned integer expressions user.cpp:67: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'bool check_reduce(std::vector<edge, std::allocator<edge> >, int)': user.cpp:80: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void reduce_more(int)': user.cpp:89: warning: comparison between signed and unsigned integer expressions user.cpp:96: warning: comparison between signed and unsigned integer expressions user.cpp:101: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'int main()': user.cpp:129: warning: comparison between signed and unsigned integer expressions