Compilare: user.cpp: In function ‘bool okp(int)’: user.cpp:23:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < u[y].size(); i++) ^ user.cpp: In function ‘void marcare(int, int)’: user.cpp:39:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < u[y].size(); i ++) ^ user.cpp:45:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < u[y].size(); i ++) ^ user.cpp: In function ‘int main()’: user.cpp:91:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(cin, "%d", &n); ^ user.cpp:95:33: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(cin, "%d", &x[i]); ^