Compilare: user.cpp: In function ‘void pair_them(int)’: user.cpp:60:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < list[i].size(); j++) { ^ user.cpp: In function ‘int main()’: user.cpp:73:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("colorare2.in","r",stdin); ^ user.cpp:74:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("colorare2.out","w",stdout); ^ user.cpp:76:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &n, &m, &k); K = k; ^ user.cpp:78:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^