Making 4 string from the given string
let s1 = " " , s2 = " " , s3 = " " , s4 = " " ; s1 = s . substring ( 0 , i ) ; s2 = s . substring ( i , i + j - i ) ; s3 = s . substring ( j , j + k - j ) ; s4 = s . substring ( k , k + s . length - k ) ;