Compilare: user.cpp: In function ‘void merge(std::vector<int>&, std::vector<int>&, std::vector<int>&)’: user.cpp:34:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; i<a.size() && j<b.size(); ) { ^ user.cpp:34:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; i<a.size() && j<b.size(); ) { ^ user.cpp:41:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; i<a.size(); i++) ^ user.cpp:44:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; j<b.size(); j++) ^ user.cpp: In function ‘void q_pom(int, int, int)’: user.cpp:70:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(a+m<pom[nod].size() && pom[nod][a+m]<qy1) ^ user.cpp:74:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(b+m<pom[nod].size() && pom[nod][b+m]<=qy2) ^ user.cpp:63:9: warning: unused variable ‘ans’ [-Wunused-variable] int ans = 0; ^ user.cpp: In function ‘int main()’: user.cpp:159:34: 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:160:36: 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:162:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:164:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&v[i].y); ^ user.cpp:170:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&m); ^ user.cpp:173:46: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&qx1,&qx2,&qy1,&qy2); ^ user.cpp: In function ‘int query()’: user.cpp:108:1: warning: control reaches end of non-void function [-Wreturn-type] } ^