#include <stdio.h>

int main()
{
    char equation[1000] = "x^(2)";
    int equationlength = strlen(equation);
    char diff = 'x';
    int state1 = 0;
    char equationderivative[1000];
    char power[1000];
    char newpower[1000];
    char piece1[1000]; // used to find the newpower
    int piece2 = 0; // (might be used) used to find the newpower in addition to piece1
    // checking if the equation contains the variable of differentiation:
    for(int i = 0; i < equationlength; i++){
        if(equation[i] == diff){
            state1 = 1;
        }
    }
    // if state1 = 1, then differentiate. Else, return zero because the derivative of
    // constant is zero.
    if(state1 == 0){
        equationderivative[0] = '0';
    }
    if(state1 == 1){
        // find power:
        for(int j = 0; j < equationlength; j++){
            if(equation[j-1] == '^'){
                for(int i = 0; i < 1000; i++){
                    if(equation[j] == '\0'){
                        break;
                    }
                    power[i] = equation[j];
                    j++;
                }
                break;
            }
        }
        //printf("%s",power);
        // next step is to apply the power rule:
        int powerlength = strlen(power);
        for(int i = 0; i < powerlength; i++){
            if(power[i] == ')'){
                newpower[i] = '-';
                newpower[i+1] = '1';
                newpower[i+2] = power[i];
                break;
            }
            newpower[i] = power[i];
        }
        //printf("%s",newpower);
        // now we just made our newpower. The next step is to assemble the derivative:
        int newpowerlength = strlen(newpower);
        for(int i = 0; i < powerlength; i++){
            equationderivative[i] = power[i];
        }
        int derivativelength1 = strlen(equationderivative);
        equationderivative[derivativelength1] = '*';
        //printf("%s",equationderivative);
        //int derivativelength2 = strlen(equationderivative);
        int var = 0;
        for(int derivativelength2 = strlen(equationderivative); derivativelength2 < 1000; derivativelength2++){
            equationderivative[derivativelength2] = equation[var];
            if(equation[var] == '^'){
                var = 0;
                break;
            }
            var++;
        }
        for(int derivativelength3 = strlen(equationderivative); derivativelength3 < 1000; derivativelength3++){
            if(newpower[var] == '\0'){
                var = 0;
                break;
            }
            equationderivative[derivativelength3] = newpower[var];
            var++;
        }
    }
    printf("%s",equationderivative);
}