#include using namespace std; typedef signed long long ll; #undef _P #define _P(...) (void)printf(__VA_ARGS__) #define FOR(x,to) for(x=0;x<(to);x++) #define FORR(x,arr) for(auto& x:arr) #define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++) #define ALL(a) (a.begin()),(a.end()) #define ZERO(a) memset(a,0,sizeof(a)) #define MINUS(a) memset(a,0xff,sizeof(a)) //------------------------------------------------------- int N,M; ll A[101010],B[101010]; ll dp[101010][2]; ll AS,BS; void solve() { int i,j,k,l,r,x,y; string s; cin>>N>>M; ll ma=0; FOR(i,N) { cin>>A[i]>>B[i]; dp[i+1][0]=max(dp[i][0],dp[i][1])+max(A[i],B[i]); dp[i+1][1]=dp[i][1]+max({B[i],A[i]*(M-1)+B[i],A[i]*M}); ma=max({ma,dp[i+1][0],dp[i+1][1]}); } cout<