#include <stdio.h>
#include <math.h>

 int main(void){

 int t1, r, n, tf, t,  somatoria, i, i2;
 char p;

 printf("t1 = ");
 scanf("%d", &t1);
 printf("\nr = ");
 scanf("%d", &r);
 printf("\nn = ");
 scanf("%d", &n);
 printf("a ou g? ");
 scanf("%*c%c", &p);

 if(p == 'a'){

    for(i = 1; i <= n; i+r){
        i2 = 1;
        printf("termo n %d = %d", i2, i);
        i2++;
    }
    tf = (t1+(n-1))*r;
    somatoria = ((t1+tf)*n)/2;
    printf("somatoria = %d", somatoria);

 }else if(p == 'g'){
    for(i = 0; i < n; i++){
        t = t1*(pow(r, i));
        printf("termo n %d = %d", i, t);
    }
    tf = t1*(pow(r, n));
    somatoria = (t1*(r*pow(r, n))-1)/(r-1);

    printf("somatoria = %d", somatoria);

 }

 return 0;
 }