Code Bot compiler - 在线编译器 C. This code calculates the number of grains on a chessboard square (2^(n-1)) and tries to print it. The `grains` function works correctly for positive `n`, but the `main` function has a syntax error when calling it.

在线编译器 C

#include <stdio.h> unsigned long long grains(int n) { unsigned long long res = 1; for (int i = 1; i < n; i = i + 1) { res = res * 2; } return res; } int main() { int x; scanf("%d", &x); printf("%d", unsigned long long grains(int x)); }

This code calculates the number of grains on a chessboard square (2^(n-1)) and tries to print it. The `grains` function works correctly for positive `n`, but the `main` function has a syntax error when calling it.

- In `printf`, the function call `unsigned long long grains(int x)` is written incorrectly. In C, you call a function by its name with arguments, not by redeclaring its type and parameters.
- The `printf` format specifier `%d` is for `int`, but the function returns `unsigned long long`. You need a different format specifier for that type.