View Compilation Error

0_0_13724840_15744.cpp:75:13: error: stray '\' in program
             len=sum\num;
             ^
0_0_13724840_15744.cpp: In function 'int solve()':
0_0_13724840_15744.cpp:75:21: error: expected ';' before 'num'
             len=sum\num;
                     ^