I couldnt find a way to fix this error. Its my homeworkand its due soon. I$\text{'}$m trying to optimize a personnel scheduling problem with lingo $.$

sets:

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EMPLOYEES$/1.\mathrm{.}11/$;

SHIFTS$/1.\mathrm{.}2/$;

DAYS$/1.\mathrm{.}30/$;

GRUP$1($EMPLOYEES$,$SHIFTS,DAYS$)$:X;

ENDSETS

@gin$($EMPLOYEES$($i$))$;

MIN$=$ @SUM$($EMPLOYEES$($i$)$: @SUM$($DAYS$($J$)$: @SUM$($SHIFTS$($K$))))$: X$($i$,$J$,$K$)$;

@for$($DAYS$($J$)$: @FOR$($SHIFTS$($K$)$: @SUM$($EMPLOYEES$($i$)$:X$($i$,$J$,$K$))>=1))$;

@for$($EMPLOYEES$($i$)$: @FOR$($DAYS$($J$)$: @FOR$($SHIFTS$($K$)$:X$($i$,$J$,$K$)<=1)))$;

@sum$($EMPLOYEES$($i$)$: @SUM$($DAYS$($J$)$: @SUM$($SHIFTS$($K$)$:X$($i$,$J$,$K$))))<=24$;

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I$\text{'}$m trying to make a personnel schedule problem with lingo. I quess something is wrong with my sets. For the employee set program uses the decimals I dont know why and how to fix this.$$t also gives me the error code $161$ 'index variables may not share names with other variables'