View Compilation Error

0_0_20129333_31330.cpp: In function 'matrix mul(matrix, matrix)':
0_0_20129333_31330.cpp:15:29: error: 'memset' was not declared in this scope
     memset(c.f,0,sizeof(c.f));
                             ^
0_0_20129333_31330.cpp: In function 'matrix pow_mod(matrix, long long int)':
0_0_20129333_31330.cpp:33:29: error: 'memset' was not declared in this scope
     memset(s.f,0,sizeof(s.f));
                             ^