Compilare: main.cpp: In function 'int main()': main.cpp:15:20: warning: array subscript has type 'char' [-Wchar-subscripts] fr[s[i - 1]] = (1LL * fr[s[i - 1]] + n - i + 1) % mod; ^ main.cpp:15:42: warning: array subscript has type 'char' [-Wchar-subscripts] fr[s[i - 1]] = (1LL * fr[s[i - 1]] + n - i + 1) % mod; ^ main.cpp:21:20: warning: array subscript has type 'char' [-Wchar-subscripts] fr[s[i - 1]] = (fr[s[i - 1]] - (n - i + 1) + mod) % mod; ^ main.cpp:21:36: warning: array subscript has type 'char' [-Wchar-subscripts] fr[s[i - 1]] = (fr[s[i - 1]] - (n - i + 1) + mod) % mod; ^ main.cpp:22:37: warning: array subscript has type 'char' [-Wchar-subscripts] int aux = (sum - fr[s[i - 1]] + mod) % mod; ^