编辑代码

#include<stdio.h>

int c, d;

int func(int a, int b)
{
    if(a == 1) {
        return (b * c + d) % 10;
    } else if(a >= 2) {
        return func(a- 1, func(a - 1, b));
    }
}

int main() 
{ 
    int a, b;

    scanf("%d %d %d %d", &a, &b, &c, &d);

    printf("%d", func(a, b));
    
    return 0; 
}