Compilare: user.cpp: In function ‘bool okp(int)’: user.cpp:19:34: 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:56:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < u[y].size(); i ++) ^ user.cpp:62:38: 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:106:29: warning: NULL used in arithmetic [-Wpointer-arith] for(int i = 0; ch[i] != NULL; i ++) ^ user.cpp:102:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &n); ^ user.cpp:104:26: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(ch, 700005, in); ^ user.cpp:105:26: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(ch, 700005, in); ^