If it is not possible to form n digit number from the given m digits without repetition
if ( $ m < $ n ) { return -1 ; } for ( $ i = 0 ; $ i < $ m ; $ i ++ ) { if ( $ arr [ $ i ] == 0 ) $ isZero = 1 ; if ( $ arr [ $ i ] == 5 ) $ isFive = 1 ; }