Compilare: user.cpp: In function ‘void build(int, int, int)’: user.cpp:26:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < g[lt].size() && j < g[rt].size()) ^ user.cpp:26:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < g[lt].size() && j < g[rt].size()) ^ user.cpp:40:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < g[lt].size()) ^ user.cpp:46:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j < g[rt].size()) ^ user.cpp: In function ‘int main()’: user.cpp:72:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.in" , "r" , stdin); ^ user.cpp:73:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.out" , "w" , stdout); ^ user.cpp:75:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &n); ^ user.cpp:77:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &v[i]); ^ user.cpp:81:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &m); ^ user.cpp:84:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &a); ^ user.cpp:85:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &b); ^ user.cpp:86:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &x); ^ user.cpp:87:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &y); ^