#include<stdlib.h>#include<stdio.h>#include<string.h>#include<math.h>#include<map>#include<algorithm>#include<vector>#include<set>#include<iostream>#include<string>using namespace std;#define CC(x,i) do{memset(x,i,sizeof(x));}while(0)#define inf 0x7f7f7f7f#define PII pair<int,int>#define VI vector<int>#define mp make_pair#define X first#define Y second#define pb push_back#define lb lower_bound#define ub upper_bound#define all(x) x.begin(),x.end()#define uniq(x) do{sort(all(x));x.resize(unique(all(x))-x.begin());}while(0)#define two(x) (1ll<<(x))#define forn(i,l,r) for(int i=(int)(l);i<(int)(r);i++)#define rep(i,x) for(int i=0;i<(int)(x);i++)typedef long long LL;LL nn,ff,bb;LL p[1024],b[1024];LL mubiao=0;int ok(LL ti){LL tot=0;rep(i,nn){if(b[i]==0){LL tt=ti-p[i]-ff;if(tt>=0){tot+=tt/(2*ff)+1;}}else{LL tt=ti-(ff-p[i]);if(tt<0)return 0;tot+=tt/(2*ff)+1;}}return tot>=mubiao;}int main ( int argc, char *argv[] ){int TT;cin>>TT;while(TT--){cin>>nn>>ff>>bb;rep(i,nn)cin>>p[i]>>b[i];mubiao=bb;rep(i,nn)mubiao+=b[i];if(ok(0)){cout<<0<<endl;continue;}LL mLeft=0,mRight=3000000000LL;while(mLeft<mRight-1){LL mid=(mLeft+mRight)/2;if(ok(mid))mRight=mid;else mLeft=mid;}cout<<mRight<<endl;}return EXIT_SUCCESS;}
