Compilare: user.cpp: In function ‘void solve2()’: user.cpp:53:15: warning: unused variable ‘k’ [-Wunused-variable] int i, j, k, s; ^ user.cpp: In function ‘void solve3()’: user.cpp:81:15: warning: unused variable ‘k’ [-Wunused-variable] int i, j, k, elem; ^ user.cpp: In function ‘void solve4()’: user.cpp:90:15: warning: unused variable ‘k’ [-Wunused-variable] int i, j, k, elem; ^ user.cpp: In function ‘int main()’: user.cpp:114:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("treid.in", "r", stdin); ^ user.cpp:115:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("treid.out", "w", stdout); ^ user.cpp:117:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &n, &m); ^ user.cpp:120:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &a [i][j]); ^