7
10
20
1-4
1-3
1-7
1-9
4-5
3+6
7-8
9-10
5+2
6+2
8-2
10+2
7+9
9+3
3+4
4+7
5+8
8+10
10+6
6-5
6
12
1-2
2-3
3-4
4-1
1-5
2-5
3-5
4-5
1-6
2-6
3-6
4-6
6
12
1+2
2+3
3+4
4-1
1-5
2+5
3+5
4+5
1+6
2-6
3-6
4+6
6
12
1+2
2+3
3+4
4-1
1+5
2+5
3+5
4+5
1-6
2+6
3-6
4+6
6
12
1-2
2-3
3-4
4-1
1-5
2-5
3-5
4-5
1-6
2-6
3-6
4-6
6
12
1+2
2+3
3-4
4-1
1-5
2+5
3+5
4+5
1-6
2-6
3-6
4+6
16
32
1-2
1-3
1-5
1-7
2-4
2-8
2-9
3-4
3-6
3-11
4-10
4-12
5-6
5+7
5+13
6+11
6+15
7-8
7+13
8+9
8+14
9-10
9-14
10+12
10-16
11-12
11+15
12+16
13-14
13-15
14-16
15-16