Main.cc:4:1: error: expected ‘,’ or ‘;’ before ‘using’ using namespace std; ^~~~~ Main.cc: In function ‘int main()’: Main.cc:15:14: error: ‘min’ was not declared in this scope w[i]=min(w[i],w[i+1]); ^~~ Main.cc:15:14: note: suggested alternative: In file included from /usr/include/c++/7/algorithm:62:0, from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:65, from Main.cc:1: /usr/include/c++/7/bits/stl_algo.h:3456:5: note: ‘std::min’ min(initializer_list<_Tp> __l, _Compare __comp) ^~~ Main.cc:30:9: error: ‘cin’ was not declared in this scope cin>>x>>y; ^~~ Main.cc:30:9: note: suggested alternative: In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:75:0, from Main.cc:1: /usr/include/c++/7/iostream:60:18: note: ‘std::cin’ extern istream cin; /// Linked to standard input ^~~ Main.cc:38:16: warning: suggest parentheses around ‘+’ inside ‘>>’ [-Wparentheses] int mid = l + r >> 1; ~~^~~ Main.cc:9:10: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&q); ~~~~~^~~~~~~~~~~~~~ Main.cc:11:14: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&w[i]); ~~~~~^~~~~~~~~~~~