Compilare: user.cpp: In function ‘bool exist(int)’: user.cpp:10:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<a[m].size();i++){ ^ user.cpp: In function ‘void del(int)’: user.cpp:29:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a[m].size();i++){ ^ user.cpp: In function ‘int main()’: user.cpp:9:13: warning: ‘c’ may be used uninitialized in this function [-Wmaybe-uninitialized] int m=x%mod; ^ user.cpp:41:15: note: ‘c’ was declared here int b,c; ^ user.cpp:42:9: warning: ‘b’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (b==1) add(c); ^