Compilare: user.cpp: In function ‘int main()’: user.cpp:24:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(!dq[firstc].empty()) maxlen = std::max(maxlen, 1 + d[dq[firstc].front()]); ^ user.cpp:24:74: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(!dq[firstc].empty()) maxlen = std::max(maxlen, 1 + d[dq[firstc].front()]); ^ user.cpp:25:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!dq[lastc].empty() && maxlen >= d[dq[lastc].back()]) dq[lastc].pop_back(); ^ user.cpp:25:57: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!dq[lastc].empty() && maxlen >= d[dq[lastc].back()]) dq[lastc].pop_back(); ^ user.cpp:25:76: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!dq[lastc].empty() && maxlen >= d[dq[lastc].back()]) dq[lastc].pop_back(); ^ user.cpp:26:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] dq[lastc].push_back(i); ^ user.cpp:13:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d%d", &n, &k); ^