单项选择题

有以下程序:
#include ＜stdio.h＞
main( )
ehar c1,c2,c3,c4,c5,c6;
scanf( "% c% c% c% c", &c1, &c2, &c3, &c4);
c5 = getehar( ); c6 = getchar( );
putehar(c1); putehar(c2);
printf("%c%c\n", c5, c6);
23 ＜回车＞
45678 ＜回车＞