Compilare: main.cpp: In function 'void FormKey()': main.cpp:22:14: warning: array subscript has type 'char' [-Wchar-subscripts] key[c] = ++cnt; ^ main.cpp:25:14: warning: array subscript has type 'char' [-Wchar-subscripts] key[c] = ++cnt; ^ main.cpp:28:14: warning: array subscript has type 'char' [-Wchar-subscripts] key[c] = ++cnt; ^ main.cpp: In function 'int main()': main.cpp:41:32: warning: array subscript has type 'char' [-Wchar-subscripts] h1 = (h1 * BASE + key[x]) % MOD; ^ main.cpp:48:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); ++i) { ~~^~~~~~~~~~ main.cpp:49:35: warning: array subscript has type 'char' [-Wchar-subscripts] h2 = (h2 * BASE + key[b[i]]) % MOD; ^ main.cpp:55:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = a.size(); i < b.size(); ++i) { ~~^~~~~~~~~~ main.cpp:56:38: warning: array subscript has type 'char' [-Wchar-subscripts] h2 = h2 - key[b[i - a.size()]] * pk % MOD; ^ main.cpp:59:41: warning: array subscript has type 'char' [-Wchar-subscripts] h2 = (h2 * BASE % MOD + key[b[i]]) % MOD; ^