Compilare: main.cpp: In function 'void Copy()': main.cpp:46:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < toclear.size(); ++i) { ~~^~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:108:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("volum.in", "r", stdin); ^ main.cpp:109:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("volum.out", "w", stdout); ^ main.cpp:110:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:113:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a[i][j]); ^