Compilare: user.cpp: In function ‘int cst(int, int)’: user.cpp:21:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(st < s.size()) { ^ user.cpp:22:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j < k && st+j < s.size(); j++) { ^ user.cpp:23:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[s[st+j]] ++; ^ user.cpp:24:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] nel[s[st+j]] += (f[s[st+j]] > 1); ^ user.cpp:24:39: warning: array subscript has type ‘char’ [-Wchar-subscripts] nel[s[st+j]] += (f[s[st+j]] > 1); ^ user.cpp:26:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j < k && st+j < s.size(); j++) { ^ user.cpp:27:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[s[st+j]] --; ^ user.cpp:33:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(lua[z] > 0) { ^ user.cpp:34:32: warning: array subscript has type ‘char’ [-Wchar-subscripts] ch.push_back({lua[z], 0}); ^ user.cpp:35:32: warning: array subscript has type ‘char’ [-Wchar-subscripts] ch.push_back({nel[z], 1}); ^ user.cpp:37:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[z] = nel[z] = 0; ^ user.cpp:37:21: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[z] = nel[z] = 0; ^ user.cpp: In function ‘int main()’: user.cpp:61:14: warning: array subscript has type ‘char’ [-Wchar-subscripts] lua[c]++; ^ user.cpp:62:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] lit += (lua[c]==1); ^