f91.c

#include <stdio.h>

int f91(int N) {
    if(N >= 101) {
        return (N - 10);
    }

    return f91(f91(N+11));
}

int main(void) {
    int num[250000];

    int i;
    for(i = 0; i < 250000; i++)
        num[i] = 0;

    i = 0;
    do {
        scanf("%d", &num[i]);
        i++;
    } while (num[i-1] != 0);

    i = 0;
    while(num[i] != 0) {
        printf("f91(%d) = %d\n", num[i], f91(num[i]));
        i++;
    }

    return 0;
}