Compilare: user.cpp: In function ‘int main()’: user.cpp:53:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<s.size(); i++) { ^ user.cpp:54:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] sol[s[i]] = (sol[s[i]] + comb(n-1, i)) % P; ^ user.cpp:54:30: warning: array subscript has type ‘char’ [-Wchar-subscripts] sol[s[i]] = (sol[s[i]] + comb(n-1, i)) % P; ^ user.cpp:55:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] is[s[i]] = true; ^