题目：
calls.txt部分数据如下
18620192711,15733218050,1506628174,1506628265,650000,810000
18641241020,15733218050,1509757276,1509757464,330000,620000
15778423030,15614201525,1495290451,1495290923,370000,420000
13341109505,15151889601,1492661762,1492662200,330000,460000
13341109505,13666666666,1470111026,1470111396,360000,230000
15032293356,13799999999,1495937181,1495937360,500000,630000
15733218050,13341109505,1452601976,1452602401,620000,530000
13269361119,13269361119,1487640690,1487641023,450000,430000
13799999999,15338595369,1511928814,1511929111,540000,230000
15733218050,15778423030,1542457633,1542457678,450000,530000
13341109505,17731088562,1484364844,1484365342,460000,360000
18332562075,15778423030,1522426275,1522426473,140000,120000
13560190665,18301589432,1485648596,1485648859,620000,820000
15733218050,13520404983,1538992531,1538992605,130000,150000
15778423030,13566666666,1484008721,1484009210,810000,330000
