Compilare: user.cpp: In function ‘int main()’: user.cpp:65:25: warning: use of ‘ll’ length modifier with ‘f’ type character [-Wformat=] scanf("%llf", &A[i][j]); ^ user.cpp:72:54: warning: use of ‘ll’ length modifier with ‘f’ type character [-Wformat=] for (int i = 1; i <= M; i++) printf("%llf ", Sol[i]); ^ user.cpp:58:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gauss.in","r",stdin); ^ user.cpp:59:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gauss.out","w",stdout); ^ user.cpp:65:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%llf", &A[i][j]); ^