class HelloWorld {
static int mex(int A[],int start, int end){
boolean bool[] = new boolean[A.length+1];
for(int i=start;i<=end;i++){
bool[A[i]] = true;
// System.out.println("--"+bool[A[i]]);
}
for(int i=0;i<A.length+1;i++){
if(!bool[i]){
// System.out.println(i);
return i;
}
}
return -1;
}
static void checker(int start, int end, int arr[][], int mex,int index){
if(arr.length==0){
arr[0][0] = start;
arr[0][1] = end;
arr[0][2] = mex;
return ;
}
int res = 0;
int check = 0;
for(int i=0;i<arr.length;i++){
if((start>=arr[i][0]&&start<=arr[i][1])||end>=arr[i][0]&&end<=arr[i][1]){
if(mex>arr[i][2]){
res = res+arr[i][2];
check = 1;
}
}
}
if(mex>res){
for(int i=0;i<arr.length;i++){
if((start>=arr[i][0]&&start<=arr[i][1])||end>=arr[i][0]&&end<=arr[i][1]){
if(mex>arr[i][2]){
arr[i][0] = -1;
arr[i][1] = -1;
arr[i][2] =-1;
}
}
}
arr[index][0] = start;
arr[index][1] = end;
arr[index][2]= mex;
}
}
static int result(int A[],int[][] offers){
int res = 0;
int added = 0;
int prestart=-1,preend=-1,index = 0;
int arr[][] = new int[offers.length][3];
for(int i=0;i<offers.length;i++){
int start = offers[i][0]-1;
int end = offers[i][1]-1;
int mex = mex(A, start, end);
// System.out.println(mex);
if(mex!=-1){
checker(start,end, arr, mex,index);
index++;
}}
for(int i=0;i<index;i++){
if(arr[i][0]!=-1){
res = res+arr[i][2];
}
}
return res;
}
public static void main(String[] args) {
int offers[][] = {{1,2}};
int A[] = {0,1};
System.out.println(result(A,offers));
}
}