void RMQ_init()
{
for(int i=1; i<=n; i++) dp[i][0]=s[i];
for(int j=1; (1<<j)<=n; j++)
for(int i=1;i+(1<<j)-1<=n;i++)
dp[i][j]=max(dp[i][j-1],dp[i+(1<<(j-1))][j-1]);
}
int RMQ(int L,int R)
{
int k=0;
while((1<<(k+1))<=R-L+1) k++;
return max(dp[L][k],dp[R-(1<<k)+1][k]);
}