Compilare: main.cpp: In function 'void solve()': main.cpp:18:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();i++) dp[i][i] |= prev1[(s[i]-'a')]; ~^~~~~~~~~ main.cpp:19:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int l=2;l<=s.size();l++) ~^~~~~~~~~~ main.cpp:20:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i+l-1<s.size();i++) ~~~~~^~~~~~~~~