Compilare: user.cpp: In function ‘void solve()’: user.cpp:24:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (ii=0; ii<v.size(); ii++) ^ user.cpp:26:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (jj=0; jj<A[v[ii]].size(); jj++) ^ user.cpp:29:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (jj=0; jj<A[i].size(); jj++) ^ user.cpp: In function ‘int main()’: user.cpp:75:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fof.in", "r", stdin); ^ user.cpp:76:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fof.out", "w", stdout); ^ user.cpp:78:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:83:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^