BEGIN{
    FS=",";
    first="";
    second="";
    line="";
}
{
    line=""
    for(c=1;c<=NF;++c) {
        if(c==i) {
            first=$c;
        }
        if(c==j) {
            second=$c;
        }
    }
    for(c=1;c<=NF;++c) {
        if(c!=i && c!=j)
            line=line$c;
        if(c==i)
            line=line second;
        if(c==j)
            line=line first;
        if(c!=NF)
            line=line";";
    }
    print line;
}