function n1( img ) { document.sn1.src = img; } 
function n2( img ) { document.sn2.src = img; }
function n3( img ) { document.sn3.src = img; }
function n4( img ) { document.sn4.src = img; }
function n5( img ) { document.sn5.src = img; }
function n6( img ) { document.sn6.src = img; }