Rightmost different bit

problem id:---http://practice.geeksforgeeks.org/problems/rightmost-different-bit/0

code:--

#include <bits/stdc++.h>

using namespace std;
#define ll   long long
#define      pii               std::pair<int,int>
#define      vi                std::vector<int>
#define      vll               std::vector<long long>
#define      mp(a,b)           make_pair(a,b)
#define      pb(a)             push_back(a)
#define sc(x)   scanf("%d",&x)
#define scll(x)   scanf("%lld",&x)
#define sc2(x,y)   scanf("%d%d",&x,&y)
#define sc3(x,y,z)   scanf("%d%d%d",&x,&y,&z)
#define     pf(x)   printf("%d ",x)
#define     pf2(x,y)   printf("%d %d ",x,y)
#define     pf3(x,y,z)   printf("%d %d %d ",x,y,z)
#define pfnl()   putchar('\n');
#define      each(it,s)        for(auto it = s.begin(); it != s.end(); ++it)
#define      rep(i, n)         for(int i = 0; i < (n); ++i)
#define rep2(i,j,n)   for(int i = j; i < (n); ++i)
#define      fill(a)           memset(a, 0, sizeof (a))
#define      sortA(v)          sort(v.begin(), v.end())
#define      sortD(v)          sort(v.begin(), v.end(), greater<auto>())
#define      X                 first
#define      Y                 second
#define gc() getchar()

#define debug(x) cerr<<"debug->"<<#x<<"::"<<x<<endl
#define debug2(x,y) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\n"
#define debug3(x,y,z) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\t"<<#z<<" :: "<<z<<"\n"
#define MOD 1000000007

template <typename T> void scan(T &angka){
angka=0;char input=gc();T kali=1;
while(!(48<=input&&input<=57)){ if(input=='-') kali=-1;input=gc();}
while(48<=input&&input<=57) angka=(angka<<3)+(angka<<1)+input-48,input=gc();angka*=kali;
}
int main(int argc, char **argv) {
//std::ios::sync_with_stdio(false);
int t;
sc(t);
while(t--)
{
int n,m;
sc2(n,m);
int i=0,ans=-1;
while(n|| m)
{
if((n&1)^(m&1))
{
ans=i+1;
break;
}
n>>=1;
m>>=1;
++i;
}
printf("%d\n",ans);
}
return 0;
}