View Compilation Error

0_0_26335361_28925.cpp: In function 'NUM mul(NUM, NUM)':
0_0_26335361_28925.cpp:209:27: error: expected primary-expression at end of input
   ans_num.num[i] = (c[len -
                           ^
0_0_26335361_28925.cpp:209:27: error: expected ']' at end of input
0_0_26335361_28925.cpp:209:27: error: expected ')' at end of input
0_0_26335361_28925.cpp:209:27: error: expected '}' at end of input