for AND and OR operation
else if ( s . Count == 5 ) { int a = s [ 0 ] - 48 , b = s [ 4 ] - 48 , c ; if ( s [ 2 ] == ' & ' ) { c = a & b ; } else { c = a | b ; } arr . Push ( ( char ) ( c + 48 ) ) ; } } else { arr . Push ( str [ i ] ) ; } } return arr . Peek ( ) ; }