Compilare: user.cpp: In function ‘void Solve(int)’: user.cpp:17:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < X[i].size(); j++) ^ user.cpp: In function ‘int main()’: user.cpp:23:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("radixsort.in","r",stdin); ^ user.cpp:24:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("radixsort.out","w",stdout); ^ user.cpp:25:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &N, &A, &B, &C); ^