Compilare: user.cpp: In function ‘int main()’: user.cpp:46:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < B[i].size(); ++j) { ^ user.cpp:26:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rangemode.in", "r", stdin); ^ user.cpp:27:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rangemode.out", "w", stdout); ^ user.cpp:30:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:32:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x[i]); ^ user.cpp:37:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &xx[i], &yy[i]); ^