#include <fstream>
std::ifstream f("elmaj.in");std::ofstream g("elmaj.out");int n,c,k,i,j,v[1005000];main(){f>>n;for(;i<n;i++)f>>v[i],(k&v[i]!=c)?k--:c=v[i],k++;k=0;for(;j<n;j++)if(v[j]==c)k++;(k<n/2+1)?(g<<-1):(g<<c<<" "<<k);}