Compilare: user.cpp: In function ‘void build(int, int, int)’: user.cpp:114:54: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0, j = 0; i < sgt[nd << 1].lst.size() || j < sgt[nd << 1 | 1].lst.size(); ) { ^ user.cpp:114:89: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0, j = 0; i < sgt[nd << 1].lst.size() || j < sgt[nd << 1 | 1].lst.size(); ) { ^ user.cpp:115:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == sgt[nd << 1].lst.size()) ^ user.cpp:118:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == sgt[nd << 1 | 1].lst.size()) ^ user.cpp:126:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (mnl < sgt[nd << 1].lst.size() && sgt[nd << 1].lst[mnl].y < sgt[nd].lst.back().y) ++mnl; ^ user.cpp:127:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (mnr < sgt[nd << 1 | 1].lst.size() && sgt[nd << 1 | 1].lst[mnr].y < sgt[nd].lst.back().y) ++mnr; ^ user.cpp:129:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (mxl + 1 < sgt[nd << 1].lst.size() && sgt[nd << 1].lst[mxl + 1].y <= sgt[nd].lst.back().y) ++mxl; ^ user.cpp:130:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (mxr + 1 < sgt[nd << 1 | 1].lst.size() && sgt[nd << 1 | 1].lst[mxr + 1].y <= sgt[nd].lst.back().y) ++mxr; ^ user.cpp: In function ‘int main()’: user.cpp:253:21: warning: unused variable ‘j’ [-Wunused-variable] for (int i = 1, j; i <= n; ++i) { ^ user.cpp: In member function ‘char InParser::read_ch()’: user.cpp:14:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 4096, fin); ^