C++ :

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std ;

const int MAXN = 20000 + 10 ;

int data[MAXN] ;
int emp[MAXN] ;
char str[MAXN*10] ;

int n = 0 ;

void init() {
    n = 0 ;
    int tmp = 0 ;
    bool has = false ;
    for( int i = 0 ; str[i] != '\0' ; i ++ ) {
        if( str[i] >= '0' && str[i] <= '9' ) {
            tmp = tmp * 10 + str[i] - '0' ;
            has = true ;
        }
        else if( has ) {
            data[n++] = tmp ;
            tmp = 0 ;
            has = false ;
        }
    }
    if( has ) data[n++] = tmp ;
}


int main() {
    char c ;
    while( gets(str) ) {
        init() ;
//        sort( data , data + n ) ;
        for( int i = 1 ; i < n ; i ++ ) emp[i] = data[i] - data[i-1] - 1 ;
        int jud = 0 ;
        for( int i = 1 ; i < n ; i += 2 ) jud ^= emp[i] ;
        if( jud == 0 ) printf("-1\n") ;
        else {
            int pos1 , pos2 ;
            for( int i = 1 ; i < n ; i += 2 ) {
                if( ( emp[i] ^ jud ) < emp[i] ) {
                    pos1 = data[i-1] ;
                    pos2 = pos1 + ( emp[i] - ( emp[i] ^ jud ) ) ;
                    break ;
                }
                else if( ( emp[i] ^ jud ) < emp[i] + emp[i+1] ) {
                    pos1 = data[i] ;
                    pos2 = pos1 + ( ( emp[i] ^ jud ) - emp[i] ) ;
                    break ;
                }
            }
            printf("%d %d\n" , pos1 , pos2 ) ;
        }
    }
    return 0 ;
}