Compilare: user.cpp: In function ‘void DFS(int)’: user.cpp:25:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a[x].size(); ++i) ^ user.cpp:32:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a[x].size(); ++i) ^ user.cpp:42:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a[x].size(); ++i) ^ user.cpp: In function ‘void Solve(int)’: user.cpp:53:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a[x].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:80:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < a[i].size(); ++j) ^ user.cpp:68:36: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d %d %d",&N,&M,&R); ^ user.cpp:71:34: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d %d",&x,&y); ^