std::vector i std::pair - jak to połączyć?

#include <cstdio>
#include <vector>
using namespace std;
int main()
{
    int c, i, j, a, p, x, y, z, k, index, size;
    scanf( "%d", & c );
    for( i = 0; i < c; i++ )
    {
       
        scanf( "%d", & a );
        vector < pair < int, int > >* us = new vector < pair < int, int > >[ a ];
        us[ a ].push_back( make_pair( a, a + 1 ) );
        printf( "%d", us[ a ][ 0 ].second );
        delete[] us;
    }
   
    return 0;
}

std::vector < std::pair < int, int > > v;

for( int i = 0; i < 100; i++ )
     v.push_back( std::make_pair( 123, 456 ) );