View Compilation Error

0_0_6516677_23890.cpp: In function `int main()':
0_0_6516677_23890.cpp:30: error: `len' undeclared (first use this function)
0_0_6516677_23890.cpp:30: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6516677_23890.cpp:45: error: expected `;' before "m"