Compilare: user.cpp: In function ‘int main()’: user.cpp:41:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0, ant = 0; j < line.size(); j ++){ ^ user.cpp:42:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(ant + 1 < line.size() && line[ant + 1].first < line[j].first) ant ++; ^ user.cpp:53:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0, ant = 0; j < col.size(); j ++){ ^ user.cpp:54:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(ant + 1 < col.size() && col[ant + 1].first < col[j].first) ant ++; ^ user.cpp:30:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("zoro.in", "r", stdin); ^ user.cpp:31:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("zoro.out", "w", stdout); ^ user.cpp:33:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:38:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] line.push_back({mat[i][j], j}); ^