Compilare: user.cpp: In function ‘int main()’: user.cpp:10:9: warning: unused variable ‘i’ [-Wunused-variable] int n, i, j, m, k; ^ user.cpp:10:12: warning: unused variable ‘j’ [-Wunused-variable] int n, i, j, m, k; ^ user.cpp:8:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("flip.in", "r", stdin); ^ user.cpp:9:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("flip.out", "w", stdout); ^ user.cpp:12:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &n, &m); ^ user.cpp:14:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] FOR (j,1,m) scanf ("%d", &a[i][j]); ^