View Compilation Error

0_0_37881940_2818.cpp: In function 'int main()':
0_0_37881940_2818.cpp:9:5: error: 'int64_t' was not declared in this scope
     int64_t n, m;
     ^
0_0_37881940_2818.cpp:10:25: error: 'n' was not declared in this scope
     scanf("%lld %lld", &n, &m);
                         ^
0_0_37881940_2818.cpp:10:29: error: 'm' was not declared in this scope
     scanf("%lld %lld", &n, &m);
                             ^
0_0_37881940_2818.cpp:12:31: error: expected ')' before 'k'
     printf("%lld\n", (int64_t)k * x);
                               ^