Compilare: main.cpp: In function 'bool check(int)': main.cpp:71:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < f[n-1].size(); i++) ~~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:88:16: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized] fout << ans; ^ main.cpp:79:9: note: 'ans' was declared here int ans; ^~~