_==0 "exec" "gawk" "-f" "$0"
BEGIN{ FS="" }
NR==1{ for(i=1;i<=NF;i++){a[i]=$i} FS=" " }
NR==2{ i=$1+1;j=$2+1;t=a[i];a[i]=a[j];a[j]=t }
END{ for(i=1;i<=length(a);i++)r=r""a[i];print r }