#include<stdio.h>
#include<string.h>

int add(int, int);
int sub(int, int);

int main(int argc, char *argv[])
{
    int (*fp)();

    if(argc != 4) {
        printf("WRONG\n");
        return 1;
    }

    if(strcmp(argv[1], "+") == 0) {
        fp = add;
        printf("%d\n", (*fp)(atoi(argv[2]), atoi(argv[3])));
    } else if(strcmp(argv[1], "-") == 0) {
        fp = sub;
        printf("%d\n", (*fp)(atoi(argv[2]), atoi(argv[3])));
    } else
        printf("use + 2 3\n - 4 2\n");

    return 0;
}

int
add(int a, int b) {
    return a + b;
}

int
sub(int a, int b) {
    return a - b;
}