int setBitNumber(int n)
{
    // Below steps set bits after MSB (including MSB)

    // Suppose n is 273 (binary is 100010001). It does following
    // 100010001 | 010001000 = 110011001
    // That is, the leftmost 2 bits will be set
    n |= n>>1;

    // This makes sure 4 bits
    // (From MSB and including MSB)
    // are set. It does following
    // 110011001 | 001100110 = 111111111
    // That is, the leftmost 4 bits will be set
    // (In previous step, we have set the leftmost 2 bits already)
    n |= n>>2;

    n |= n>>4;  // Similarly, the leftmost 8 bits will be set
    n |= n>>8;  // Similarly, the leftmost 16 bits will be set
    n |= n>>16; // Similarly, the leftmost 32 bits will be set

    // Increment n by 1 so that
    // there is only one set bit
    // which is just before original
    // MSB. n now becomes 1000000000
    // Note: only work for 2's complement numbering
    n = n + 1;

    // Return original MSB after shifting.
    // n now becomes 100000000
    // Notice: this may result in undefined behavior on signed integer
    return (n >> 1);
}

// Driver code
int main()
{
   setBitNumber(273)
   return 0;
}