Compilare: user.cpp: In function ‘void read()’: user.cpp:46:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<robot.size(); ++i) ^ user.cpp: In function ‘void convex_hull(std::vector<std::pair<int, int> >&)’: user.cpp:76:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<poly.size(); ++i) ^ user.cpp:90:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<poly.size(); ++i) ^ user.cpp: In function ‘void get_newob()’: user.cpp:104:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<ob[i].size(); ++j) ^ user.cpp:105:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k=0; k<robot.size(); ++k) ^ user.cpp: In function ‘void build_graph()’: user.cpp:124:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<newob[i].size(); ++j) ^ user.cpp: In function ‘bool adj(int, int)’: user.cpp:134:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int h=0; h<newob[k].size(); ++h) ^ user.cpp: In function ‘void dijkstra()’: user.cpp:157:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1; i<graph.size(); ++i) ^ user.cpp:174:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<graph.size(); ++i) ^