新手，照着书敲的，为啥一运行就提示错误呢，求解啊！谢谢。

#include <stdio.h>
int main( )
{
    int max(int x, int y);
    int a, b, c;
    scanf("%d,%d", &a, &b);
    c = max(a, b);
    printf("zuidazhi=%d\n",c);
    return 0;
}
int max(int x, int y);
{
    int z;
    if (x > y)z = x;
    else z = y;
    return(z);
}

错误提示
1>------ 已启动生成: 项目: ConsoleApplication1, 配置: Debug Win32 ------
1>  2.c
1>e:\cdemo\consoleapplication1\consoleapplication1\2.c(6): warning C4996: 'scanf': This function or variable may be unsafe. Consider using scanf_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
1>  c:\program files (x86)\windows kits\10\include\10.0.10150.0\ucrt\stdio.h(1270): note: 参见“scanf”的声明
1>e:\cdemo\consoleapplication1\consoleapplication1\2.c(12): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
1>e:\cdemo\consoleapplication1\consoleapplication1\2.c(17): error C2059: 语法错误:“}”
========== 生成: 成功 0 个，失败 1 个，最新 0 个，跳过 0 个 ==========