very very easy
1+1
2
7+7
14
13+13
26
19+19
38
100+100
200
2+2
4
8+8
16
14+14
28
20+20
40
200+200
400
3+3
6
9+9
18
15+15
30
21+21
42
300+300
600
4+4
8
10+10
20
16+16
32
22+22
44
400+400
800
5+5
10
11+11
22
17+17
34
23+23
46
500+500
1000