Compilare: user.cpp: In function ‘int BFS()’: user.cpp:24:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < a[x].size(); ++ j) ^ user.cpp: In function ‘int main()’: user.cpp:48:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a[n].size(); ++ i) ^ user.cpp:39:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(F, "%d %d ", &n, &m); ^ user.cpp:42:42: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(F, "%d %d %d", &x, &y, &z); ^