View Compilation Error

0_0_6361004_16769.cpp: In function `int main()':
0_0_6361004_16769.cpp:19: error: `Mat' undeclared (first use this function)
0_0_6361004_16769.cpp:19: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6361004_16769.cpp:19: error: expected `;' before "A"
0_0_6361004_16769.cpp:20: error: `mod' undeclared (first use this function)
0_0_6361004_16769.cpp:21: error: `A' undeclared (first use this function)