View Compilation Error

0_0_38349438_13545.cpp:13:1: error: '__int64_t' does not name a type
 __int64_t c(int a,int b) 
 ^
0_0_38349438_13545.cpp: In function 'int main()':
0_0_38349438_13545.cpp:51:38: error: 'c' was not declared in this scope
                 printf("%I64d ",c(i,j));
                                      ^
0_0_38349438_13545.cpp:52:35: error: 'c' was not declared in this scope
             printf("%I64d\n",c(i,j));
                                   ^