View Compilation Error

0_0_9792955_5118.cpp: In function `std::string st_sum(std::string, std::string)':
0_0_9792955_5118.cpp:41: error: expected primary-expression before '%' token
0_0_9792955_5118.cpp:41: error: expected primary-expression at end of input
0_0_9792955_5118.cpp:41: error: expected `;' at end of input
0_0_9792955_5118.cpp:41: error: expected `}' at end of input
0_0_9792955_5118.cpp:41: error: expected `}' at end of input