Compilare: user.cpp: In function ‘int main()’: user.cpp:9:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "diff.in", "r", stdin ); ^ user.cpp:10:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "diff.out", "w", stdout ); ^ user.cpp:12:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d%d", &n, &m ); ^ user.cpp:15:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d", &k ); ^ user.cpp:43:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d", &k ); ^ user.cpp:39:14: warning: ‘j’ may be used uninitialized in this function [-Wmaybe-uninitialized] v[l].st=j; ^