Compilare: user.cpp: In function ‘void decrease(int)’: user.cpp:20:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j < A[i].size(); j++) { ^ user.cpp: In function ‘bool is_marked(int)’: user.cpp:29:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i < marked.size(); i++) { ^ user.cpp: In function ‘void bfs(int)’: user.cpp:37:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j < A[i].size(); j++) { ^ user.cpp:44:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j < A[i].size(); j++) { ^ user.cpp: In function ‘int main()’: user.cpp:71:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i < marked.size(); i++) { ^