Compilare: main.cpp: In function 'bool ok(int)': main.cpp:40:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(poz+mi-1<v[s[i]-'a'].size()) ~~~~~~~~^~~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:56:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(nxt[j]<v[j].size()) ~~~~~~^~~~~~~~~~~~